Patent Publication Number: US-7591141-B2

Title: Electronic control system for insulated ice compartment for bottom mount refrigerator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part application of U.S. application Ser. No. 11/139,237, filed May 27, 2005, entitled INSULATED ICE COMPARTMENT FOR BOTTOM MOUNT REFRIGERATOR, herein incorporated by reference in its entirety. 
     This application does not claim priority, but hereby incorporates by reference in their entirety, provisional application Ser. No. 60/613,241 filed Sep. 27, 2004, entitled APPARATUS AND METHOD FOR DISPENSING ICE FROM A BOTTOM MOUNT REFRIGERATOR, and U.S. application Ser. No. 11/131,701, filed May 18, 2005, entitled REFRIGERATOR WITH INTERMEDIATE TEMPERATURE ICEMAKING COMPARTMENT. 
    
    
     BACKGROUND OF THE INVENTION 
     Household refrigerators generally come in three structural styles: (1) a side-by-side model wherein the freezer and refrigerator compartments are side by side; (2) a top mount model wherein the freezer compartment is located above the refrigerator compartment; and (3) a bottom mount model wherein the freezer compartment is mounted below the refrigerator compartment. An icemaker is normally provided in the freezer compartment of all three models. A door mounted ice dispenser is often provided in a side-by-side refrigerator and in a top mount refrigerator so that a person can add ice to a glass without opening the freezer or refrigerator door. However, a door mounted ice dispenser normally is not been provided in bottom mount refrigerators, since the freezer door is too low, and there are difficulties in transporting ice from the freezer compartment to the refrigerator compartment which precludes a dispenser in the refrigerator compartment door. However, it is desirable to have an ice dispenser in the refrigerator compartment of a bottom mount refrigerator. 
     Providing an icemaking compartment within the fresh food compartment of a refrigerator presents numerous issues, both structural and functional. For example, the fresh food compartment is normally about 40° F., while an ice compartment needs to be less than 32° F. in order to make ice effectively and efficiently and is typically at, or about 0° F. Maintaining and controlling the temperature within the icemaking compartment requires insulation, seals, appropriate airflow, and a control system. Placing the icemaking compartment within the fresh food compartment of the refrigerator also requires consideration of electrical connections of the icemaker and the supply of water to the icemaker. The method of manufacturing of such an icemaking compartment within the fresh food compartment of a refrigerator also raises novel and unique considerations which are not factors for an icemaking compartment mounted in a freezer. 
     U.S. Pat. No. 6,735,959 issued to Najewicz discloses a thermoelectric icemaker placed within the fresh food compartment of a bottom mount refrigerator that may be dispensed through the fresh food door. Najewicz forms ice within the fresh food compartment using the thermoelectric icemaker even though the compartment is above a freezing temperature. Although Najewicz provides for a duct that runs from the freezer compartment to the thermoelectric icemaker, the cold air from the duct is used to remove heat from the thermoelectric icemaker. Najewicz has many problems that must be overcome in order to be practical including the removal of unfrozen water, rapid ice body formation, prolonged ice storage, etc. The present invention overcomes these problems. 
     BRIEF SUMMARY OF THE INVENTION 
     Therefore it is a primary object, feature, or advantage of the present invention to improve over the state of the art. 
     A further object, feature, or advantage of the present invention is the provision of an improved refrigerator having an icemaking compartment within the fresh food compartment. 
     Another object, feature, or advantage of the present invention is the provision of a refrigerator having a separate icemaking compartment maintained at a temperature between 0° and 32° F. 
     A further object, feature, or advantage of the present invention is the provision of a refrigerator having an insulated icemaking compartment remote from the freezer compartment. 
     Still another object, feature, or advantage of the present invention is the provision of a bottom mount refrigerator having an icemaking compartment integrally formed in the liner of the fresh food compartment. 
     Yet another object, feature, or advantage of the present invention is the provision of a bottom mount refrigerator having a modular icemaking compartment mounted in the fresh food compartment. 
     A further object, feature, or advantage of the present invention is the provision of a bottom mount refrigerator having an icemaking compartment in the fresh food compartment, and having an insulated and sealed front cover on the icemaking compartment which can be opened to provide access into the compartment. 
     Another object, feature, or advantage of the present invention is the provision of an icemaking compartment in the fresh food compartment of a bottom mount refrigerator with a single electrical connection within the icemaking compartment for the wire harness of the icemaker. 
     Another object, feature, or advantage of the present invention is the provision of an icemaking compartment in the fresh food compartment of a bottom mount refrigerator wherein the water fill tube for supplying water to the icemaker extends downwardly through a vertically disposed hole in the top wall of the refrigerator. 
     Still another object, feature, or advantage of the present invention is the provision of an icemaking compartment within the fresh food compartment of a bottom mount refrigerator wherein the water fill tube for the icemaker is exposed to ambient air to prevent freezing of water within the fill tube. 
     Yet another object, feature, or advantage of the present invention is the provision of a bottom mount refrigerator having a recessed cavity in the fresh food compartment in which a water tank is mounted. 
     A further object, feature, or advantage of the present invention is the provision of an icemaking compartment which is formed separately from and mounted into a fresh food compartment of a bottom mount refrigerator. 
     Another object, feature, or advantage of the present invention is the provision of a method of making a bottom mount refrigerator having an integral ice compartment formed in the liner of the fresh food compartment. 
     Still another object, feature, or advantage of the present invention is the provision of a control system for an ice compartment within the fresh food compartment of a refrigerator for controlling icemaking and dispensing. 
     Still another object, feature, or advantage of the present invention is the provision of a refrigerator having a fresh food compartment with an icemaking compartment therein, and an ice dispenser in the door of the fresh food compartment. 
     Another object, feature, or advantage of the present invention is the provision of a bottom mount refrigerator having an ice dispenser in the door of the refrigerator, also known as the fresh food, compartment. 
     Another object, feature, or advantage of the present invention is the provision of an icemaker in the refrigerator compartment of a bottom mount refrigerator, with a cold air duct to provide air from the freezer compartment to the icemaker. 
     Still another object, feature, or advantage of the present invention is the provision of an icemaker in the refrigerator compartment of a bottom mount refrigerator having efficient and timely icemaking capacity. 
     It is a further object, feature, or advantage of the present invention to provide a bottom mount refrigerator that dispenses ice and water through the door. 
     It is a still further object, feature, or advantage of the present invention to provide a refrigerator that is energy efficient. 
     Another object, feature, or advantage of the present invention is to provide a refrigerator that enhances safety. 
     Yet another object, feature, or advantage of the present invention is to provide a refrigerator that provides convenience to users. 
     A further object, feature, or advantage of the present invention is to provide a refrigerator that is aesthetically pleasing to users. 
     A still further object, feature, or advantage of the present invention is to provide a refrigerator with a control system design that minimizes the complexity and the number of components necessary. 
     Another object, feature, or advantage of the present invention is to provide a refrigerator with a drive for the ice box/fresh food compartment damper which provides feedback. 
     Yet another object, feature, or advantage of the present invention is to provide a refrigerator with compartment light cutout. 
     A further object, feature, or advantage of the present invention is to provide a refrigerator which disables the icemaker and dispenser when the fresh food compartment door opens. 
     A still further object, feature, or advantage of the present invention is to provide a refrigerator with a menu-driven interface. 
     Another object, feature, or advantage of the present invention is to provide a refrigerator with a variable speed fan. 
     One or more of these and/or other objects, features, or advantages of the present invention will become from the specification and claims that follow. 
     The bottom mount refrigerator of the present invention has an icemaker within an insulated icemaking compartment in the fresh food or refrigerator compartment. Cold air is supplied to the icemaking compartment from the freezer compartment via a cold air duct. A return air duct extends from the icemaking compartment to the freezer compartment. The icemaking compartment also includes a vent opening for venting air to the refrigerator compartment. A fan draws or forces air through the duct from the freezer compartment to the icemaking compartment. The temperature in the ice making compartment is between 0° F. to 32° F., which is colder than the temperature of the refrigerator compartment, but not as cold as the freezer compartment. The icemaking compartment is preferably located in an upper corner of the refrigerator compartment. The door of the refrigerator compartment includes an ice dispenser to supply ice to a person without opening the refrigerator compartment door. The door may include an ice bin for storing ice from the icemaker. 
     In the improved refrigerator of the present invention, the icemaking compartment is insulated. Preferably, the icemaking compartment is formed integrally with the liner of the fresh food compartment. Alternatively, the icemaking compartment is formed separately from and mounted in the fresh food compartment. The icemaking compartment includes inner and outer shells, with insulation therebetween, as well as an insulated front cover which provides an air-tight seal with the icemaking compartment when closed, and which can be opened to provide access to the icemaker and ice bin within the icemaking compartment. The water fill tube for the icemaking compartment extends through a vertically disposed hole in the top wall of the refrigerator, and is exposed to ambient air to prevent freezing of water within the tube. The refrigerator includes a recessed cavity in the back wall in which a water tank is mounted. 
     In the method of manufacturing the icemaking compartment of the present invention, the ice compartment is preferably formed in the liner of the fresh food compartment during the molding processing using oppositely disposed forces. A three-dimensional plug forms the icemaking compartment from a rear side of the fresh food compartment liner. A front wall of the icemaking compartment is then cutout, so that an ice box can be inserted through the cutout into the icemaking compartment. 
     A control system is provided for the refrigerator for controlling the making and dispensing of ice in the icemaking compartment within the fresh food compartment of the bottom mount refrigerator. 
     In one aspect of the invention, a refrigerator includes a refrigerator cabinet, a fresh food compartment disposed within the cabinet, a freezer compartment disposed within the cabinet, an ice compartment disposed within the cabinet, and an electronic control system associated with the refrigerator and adapted to monitor and control the fresh food compartment, the freezer compartment and the ice compartment. Preferably, the ice compartment is positioned remote from the freezer compartment. Preferably also, two side-by-side fresh food compartment doors provide access to the fresh food compartment. A freezer compartment door for providing access to the freezer compartment is preferably positioned below the two side-by-side fresh food compartment doors. A dispenser is associated with one of the two side-by-side fresh food compartment doors, the dispenser is adapted for dispensing ice from the ice compartment as well as water. The control system is adapted to disable the dispenser upon opening of the fresh food compartment door associated with the dispenser. 
     According to another aspect of the present invention, the refrigerator includes an ice compartment temperature sensor associated with the ice compartment and electrically connected to the electronic control system, a fresh food compartment temperature sensor associated with the fresh food compartment and electrically connected to the electronic control system, a freezer compartment temperature sensor associated with the freezer compartment and electrically connected to the electronic control system, and an ambient temperature sensor electrically connected to the electronic control system. The control system is preferably adapted for performing the step of calculating a desired performance temperature for each of the fresh food compartment, the freezer compartment, and the ice compartment using correlations. The control system may be adapted for performing the step of calculating a desired performance temperature for each of the fresh food compartment, the freezer compartment, and the ice compartment using correlations and weighting at least partially based on prior testing to thereby improve temperature stability and food preservation. 
     According to another aspect of the invention, the refrigerator may include a variable speed evaporator fan, and a variable speed evaporator fan output from the control system. The control system is adapted for setting the variable speed evaporator fan to a plurality of rates. The control system is adapted to set the variable speed evaporator fan at a first rate when the freezer is determined to require cooling and a second rate when the freezer is determined not to require cooling and the fresh food compartment is determined to require cooling, the second rate being lower than the first rate. The control system may also be adapted to set the variable speed evaporator fan at a first rate when the freezer is determined to require cooling and a second rate when the freezer is determined not to require cooling and the ice compartment is determined to require cooling, the second rate being lower than the first rate. 
     According to another aspect of the invention, there is a direct current (DC) mullion heater electrically connected to the control system for selectively providing heat to increase overall energy efficiency of the refrigerator. 
     According to another aspect of the invention, there is a cavity heater associated with a door of the refrigerator, the cavity heater electrically connected to the control system for selectively providing heat to increase overall energy efficiency of the refrigerator. 
     According to another aspect of the invention, there is a fresh food compartment light associated with the fresh food compartment to turn the fresh food compartment light off after a set time period during which the fresh food compartment door is open. 
     According to another aspect of the invention, there is a freezer compartment light associated with the freezer compartment to turn the freezer compartment light off after a set time period during which the freezer compartment door is open. 
     According to another aspect of the invention, the control system is adapted to disable the ice maker and a dispenser on the fresh food compartment door when the fresh food compartment door opens. 
     According to another aspect of the invention, the control system is adapted for performing the step of calculating a desired performance temperature for each of the fresh food compartment, the freezer compartment, and the ice compartment using correlations. The correlation is arrived at by prior testing in a plurality of environments and usage conditions. 
     According to another aspect of the invention there is a damper for controlling air flow and the electronic control system is adapted for monitoring damper state and if the damper state indicates the damper is not properly operating, a motor output associated with the damper is pulsed to heat and thereby free the damper. The step of monitoring can include monitoring lengths and sequence of a switch state associated with the damper and determining if the sequence is outside of a tolerance level and waiting for the sequence to be within the tolerance level before determining the damper state. 
     According to another aspect of the present invention a refrigerator is provided which includes a refrigerator cabinet, at least one compartment disposed within the refrigerator cabinet, a cooling system within the refrigerator cabinet, and an electronic control system associated with the refrigerator and adapted to monitor and control temperature within the at least one compartment, the electronic control system adapted to cycle on and off the cooling system based on a cut-in temperature and a cut-out temperature associated with at least one of the at least one compartment, the electronic control system further adapted to adjust the cut-in temperature and the cut-out temperature during operation of the refrigerator to thereby improve temperature performance and energy efficiency of the refrigerator. 
     According to another aspect of the present invention, a refrigerator is provided. The refrigerator includes a refrigerator cabinet, at least two compartments disposed within the refrigerator cabinet, each of the at least two compartments having a temperature sensor for sensing temperature, and an electronic control system associated with the refrigerator, operatively connected to each of the at least two temperature sensors for monitoring temperature within the at least two compartments, the electronic control system further adapted to synchronize cooling of the at least two compartments to thereby provide consistent power consumption patterns. 
     According to another aspect of the present invention a refrigerator is provided. The refrigerator includes a refrigerator cabinet, a compartment disposed within the refrigerator cabinet, a temperature sensor associated with the compartment, and an electronic control system operatively connected to the temperature sensor and adapted for calculating a desired performance temperature for the compartment using temperature data from the temperature sensor and temperature data based on prior testing from locations within the compartment different from a position of the temperature sensor within the compartment to thereby improve temperature stability and food preservation of the refrigerator without use of additional temperature sensors within the compartment. The step of calculating can include using correlation and weighting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a bottom mount refrigerator according to the present invention. 
         FIG. 2  is a perspective view of the bottom mount refrigerator having the doors removed. 
         FIG. 3  is a view similar to  FIG. 2  showing the cold air duct and return air duct for the icemaking compartment. 
         FIG. 4  is a front elevation view of the bottom mount refrigerator of the present invention with the doors open, and illustrating the cold air and return air ducts. 
         FIG. 5  is a sectional view taken along lines  5 - 5  of  FIG. 4 . 
         FIG. 6  is a sectional view taken along lines  6 - 6  of  FIG. 4 . 
         FIG. 7  is a perspective view of the icemaker positioned within the icemaking compartment. 
         FIG. 8  is a perspective view of the fresh food compartment liner with the integrally formed icemaking compartment of the present invention. 
         FIG. 9  is a front elevation view of the liner shown in  FIG. 8  without the ice box attached. 
         FIG. 10  is a side elevation view of the liner shown in  FIG. 8 . 
         FIG. 11  is a perspective view of the ice box which mounts to the liner in accordance with one embodiment of the present invention. 
         FIG. 12  is a right side elevation view of the fresh food compartment liner showing the water tank recess formed in the rear wall. 
         FIG. 13  is a partial front elevation view of the fresh food compartment liner showing the water tank recess. 
         FIG. 14  is a rear perspective view of the fresh food compartment liner with the ice box installed within the outer shell of the fresh food compartment. 
         FIG. 15  is a front perspective view of the fresh food compartment with the ice maker and pan assembly removed for clarity. 
         FIG. 16  is a perspective view of the liner, box and air ducts provided for the icemaking compartment. 
         FIG. 17  is a front elevation view of the ice compartment with the pan assembly moved for clarity. 
         FIG. 18  is a view showing an internal portion of the icemaking compartment with a wire harness cavity in an open position. 
         FIG. 19  is a view similar to  FIG. 16  showing the wire harness cavity with a cover installed. 
         FIG. 20  is a perspective view from the front of the icemaker showing the bin and front cover in a closed position. 
         FIG. 21  is a view similar to  FIG. 14  showing the bin and front cover in an open position. 
         FIG. 22  is a perspective view of the ice pan, auger and motor assembly. 
         FIG. 23  is an exploded view of the ice pan, auger and motor assembly. 
         FIG. 24  is a rear elevation view of the bin assembly seal for the icemaking compartment. 
         FIG. 25  is a sectional view taken along lines  25 - 25  of  FIG. 24 . 
         FIG. 26  is a front view of the water cavity formed within the rear wall of the fresh food compartment, with the water tank assembly mounted therein. 
         FIG. 27  is a front view of the fresh food compartment showing the cover installed over the water tank cavity. 
         FIG. 28  is a perspective view of the water tank assembly of the present invention. 
         FIG. 29  is an exploded view of the water tank assembly of the present invention. 
         FIG. 30  is a perspective view showing the top of the refrigerator with the water fill tube cup mounted thereon. 
         FIG. 31  is an enlarged view of the water fill tube cup showing the vertical hole through which the water fill tube extends. 
         FIG. 32  is a sectional view taking along lines  32 - 32  of  FIG. 31 . 
         FIG. 33  is an exploded perspective view of the air impingement system of the present invention. 
         FIG. 34  is an assembled perspective view of the air impingement system in the ice box. 
         FIG. 35  is an assembled perspective view of the ice maker in the ice box. 
         FIG. 36  is a view showing the male mold for forming the liner of the fresh food compartment according to the preferred embodiment of the present invention. 
         FIG. 37  is a view similar to  36  showing the plug inserted for formation of the icemaking compartment. 
         FIG. 38  is a view of an alternative embodiment of an icemaking compartment formed separately from the fresh food compartment liner and mounted therein. 
         FIG. 39  is an exploded view of the separate ice compartment of the alternative embodiment. 
         FIG. 40A  is a block diagram of one embodiment of a control system according to the present invention. 
         FIG. 40B  is a block diagram of another embodiment of a control system according to the present invention. 
         FIG. 41  is a flow diagram of an executive loop according to one embodiment of the present invention. 
         FIG. 42  is a flow diagram of a calculate temperatures subroutine according to one embodiment of the present invention. 
         FIG. 43  illustrates one embodiment of a flow diagram for the adjust setpoints subroutine. 
         FIG. 44A  illustrates one embodiment of a flow diagram for the update freezer subroutine. 
         FIG. 44B  illustrates one embodiment of a flow diagram for the update freezer cuts subroutine. 
         FIG. 44C  illustrates relationships between the cooling flag, control, temperature, setpoint, cut-ins, cut-outs, and cycle time for the update freezer cuts subroutine. 
         FIG. 45A  illustrates one embodiment of a flow diagram for the update ice box subroutine. 
         FIG. 45B  illustrates one embodiment of a flow diagram for the update ice box cuts subroutine. 
         FIG. 45C  illustrates relationships between the cooling flag, control, temperature, setpoint, cut-ins, cut-outs, and cycle time for the update ice box cuts subroutine. 
         FIG. 46A  illustrates one embodiment of a flow diagram for the update fresh food subroutine. 
         FIG. 46B  illustrates one embodiment of a flow diagram for the update fresh food cuts subroutine. 
         FIG. 46C  illustrates relationships between the cooling flag, control, temperature, setpoint, cut-ins, cut-outs, and cycle time for the update fresh food cuts subroutine. 
         FIG. 47  illustrates one embodiment of a flow diagram for the update defrost subroutine. 
         FIG. 48  illustrates one embodiment of a flow diagram for the check stable cycles subroutine. 
         FIG. 49  illustrates one embodiment of a flow diagram for the scan ice maker subroutine. 
         FIG. 50  illustrates one embodiment of a flow diagram for the control compressor subroutine. 
         FIG. 51  illustrates one embodiment of a flow diagram for the control damper subroutine. 
         FIG. 52  illustrates one embodiment of a flow diagram for the control defrost heater subroutine. 
         FIG. 53  illustrates one embodiment of a flow diagram for the control evaporator fan subroutine. 
         FIG. 54  illustrates one embodiment of a flow diagram for the control ice box fan subroutine. 
         FIG. 55  illustrates one embodiment of a methodology for damper recovery. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A bottom mount refrigerator is generally designated in the drawings by the reference numeral  10 . The refrigerator  10  includes a refrigerator or fresh food compartment  12  and a freezer compartment  14 . Doors  16  are provided for the refrigerator compartment or fresh food compartment  12  and a door  18  is provided for the freezer compartment  14 . One of the doors  16  includes an ice dispenser  20 , which may also include a water dispenser. 
     Intermediate Temperature Icemaking Compartment 
     An icemaking compartment or intermediate compartment  22  is provided in the refrigerator compartment  12 . The icemaking compartment  22  is shown to be in one of the upper corners of the refrigerator, or fresh food, compartment  12 , but other locations are also within the scope of this invention. The icemaking compartment  22  has a front cover  23  that is insulated to prevent the cold air of the icemaking compartment  22  from passing into the refrigerator compartment and opening  21  is provided that mates with chute  19  of the ice dispenser  20 . A seal may be provided between the opening  21  and chute  19  to prevent cold air from passing from the icemaking compartment to the refrigerator compartment  12 . Chute  19  may be adapted to engage opening  21  upon closing of door  16 . Chute  19  and opening  21  may be opposingly angled as to provide added sealing upon closing of door  16 . Additionally, a intermediate piece maybe be used to improve the seal be between chute  19  and opening  21 . For example, a resilient seal may be used to assist in achieving this seal. Alternatively, a spring or other elastic material or apparatus may be utilize between or about the junction of chute  19  and opening  21 . Other alternatives for sealing between chute  19  and opening  21  should be evident to one skilled in the art. 
     Additionally, chute  19  should have a blocking mechanism located within or about it to assist in preventing or decreasing the flow of air or heat transfer within chute  19 . For example, a flipper door that operates by a solenoid may be placed at the opening  21  to prevent cold air from leaving the icemaking compartment  22  and entering into the refrigerator compartment. 
     Preferably, the icemaking compartment  22  includes an icemaker  50  (as described below) that forms ice in an environment that is below freezing. 
     The icemaking compartment  22  may be integrally formed adjacent the refrigerator compartment  12  during the liner forming process and insulation filling process. In such a process the intermediate compartment may be separated on at least one side from the fresh food compartment by the refrigerator liner. Alternatively, the icemaking compartment  22  may be made or assembled remotely from the fresh food compartment and installed in the fresh food compartment  12 . For example, this compartment  22  may be slid into the refrigerator compartment  12  on overhead rails (not shown) or other mounting. These methods are discussed subsequently. 
     The refrigerator  10  includes an evaporator  24  which cools the refrigerator compartment  12  and the freezer compartment  14 . Normally, the refrigerator compartment  12  will be maintained at about 40° F. and the freezer compartment  14  will be maintained at approximately 0° F. The icemaking compartment is maintained at a temperature below 32° F. or less in order to form ice, but is preferably not as cold as the freezer compartment  14 . Preferably this temperature is in the range of 20° F. The walls of the icemaking compartment are insulated to facilitate temperature control among other aspects. Grates or air vents  26  are provided in the wall  28  between the refrigerator compartment  12  and the freezer compartment  14  to allow air circulation between the compartments. 
     Air Ducts 
     A cold air duct  30  extends between the freezer compartment  14  and the icemaking or specialty compartment  22 . More particularly, the cold air duct  30  has a lower air inlet  32  within the freezer compartment  14  and an upper outlet end  34  connected to a fan  36  mounted on the back wall of the icemaker  22 . The fan  36  draws cold air from the freezer compartment and forces the cold air into the icemaker  22  so as to facilitate icemaking. It is understood that the fan  36  may be located at the inlet end  32  of the cold air duct  30 . The fan  36  controls the air flow from the freezer compartment  14  to the icemaking compartment  22  and may be a variable speed fan. The fan can be actuated by conventional means. The cold air duct  30  preferably resides within the rear wall of the refrigerator  10 , as seen in  FIG. 5 . The arrow  35  designates the air flow through the cold air duct  30 . 
     The refrigerator  10  also includes a return air duct  38  having an upper end  40  connected to the icemaker  22 , and a lower end  42  terminating adjacent one of the air grates  26 . Alternatively, the lower end  42  of the return air duct  38  may extend into the freezer compartment  14 . Preferably, the return air duct  38  resides within the rear wall of the refrigerator  10 , as seen in  FIG. 6 . 
     The icemaking compartment  22  also has an air vent for discharging air into the refrigerator compartment  14 . Thus, a portion of the air from the icemaking compartment  22  is directed through the return air duct  38  to the freezer compartment  14 , as indicated by arrow  43  in  FIG. 3 , and another portion of the icemaking compartment air is vented through the opening  44  into the refrigerator compartment  12 , as indicated by arrows  45  in  FIG. 3 . 
     As seen in  FIG. 4 , the ice is discharged from the icemaker  22  in any conventional manner. Similarly, the ice dispenser  20  functions in a conventional manner. 
     Icemaker 
     As seen in  FIG. 7 , an icemaker  50  is positioned within the icemaking compartment  22  with the ice storage area  54  with auger (not shown) removed for clarity. The icemaker  50  is mounted to an impingement duct  52 . The impingement duct receives freezer air coming from the freezer compartment through the cold air duct  30  and the fan assembly  36 . The opening  44  vents air into the refrigerator compartment  12 . The auger assembly (not shown) is provided beneath the icemaker  50  along with an ice storage bin with an insulated cover  23 . Impingement on the ice maker, as well as other aspects of ice making, is disclosed in Applicant&#39;s concurrently filed U.S. Application Publication No. US2006/0266055 A1 entitled REFRIGERATOR WITH IMPROVED ICEMAKER and is hereby incorporated by reference. 
     Control System (Generally) 
     As described in more detail below, a control system is provided that utilizes the icemaking compartment  22 , the cold air supply duct  30 , the return air duct  38 , the variable speed icemaking fan  36 , icemaking impingement air duct  52 , an icemaking compartment thermistor (not shown), an icemaking compartment electronic control damper, fresh food air return ducts  26 , and a fresh food compartment thermistor (not shown). The above components are controlled by an algorithm that prioritizes the making of ice unless the fresh food temperature exceeds the set point temperature. This prioritization is achieved as follows: 
     i. When ice is a priority, the fresh food damper is closed and the fan runs at optimum speed. In this way, supply air from the freezer compartment  14  is discharged through the impingement air duct  52 , through the ice storage area  54 , and through the icemaking compartment return air duct  38 . One of the results of this air flow, is that ice is made at the highest rate. 
     ii. When the refrigerator compartment  12  is above set point, the electronic control damper opens and the fan runs at optimum speed. The supply air to the icemaking compartment is routed almost entirely into the fresh food compartment which forces the warmer air to return to the evaporator coil of the refrigerator. This achieves a rapid return to the fresh food set point after which the damper closes and the icemaking resumes. 
     iii. When the ice bin is full and the fresh food temperature is satisfied, the icemaking fan runs at minimum speed. Aspects of this will include: reduced energy consumption; reduced sound levels; and minimized sublimation of ice. 
     The above control system permits precision control of both the icemaking compartment  22  and the refrigeration compartment  12  separately, yet minimizes the complexity and the number of component parts necessary to do so. 
     Thermoelectric Alternative 
     A thermoelectric unit (not shown) may replace the impingement duct  52  with some concessions. Preferably the thermoelectric unit would contour about the icemaker as it effectively pulls heat out of the water. Alternatively, the thermoelectric unit could be the icemaker. Regardless, it should be understood that additionally, the thermoelectric unit would require a heat sink outside of the icemaking compartment  22  to dissipate heat. A careful balance is required between the voltage of the thermoelectric unit and the temperature of the refrigerator compartment  12  if the heat sink is in the refrigerator compartment  12 . For example, the higher the voltage, the more heat will be generated that will be required to be removed from the refrigerator compartment  12 . A portion of the heat generated by the thermoelectric unit may be removed by venting freezer compartment air to the thermoelectric unit. 
     Integral Icemaking Compartment 
       FIGS. 8-25  and  33 - 35  show the preferred embodiment of the icemaking compartment  22 , wherein the compartment  22  is integrally formed with the liner  110  of the fresh food compartment  12 . The integral formation of the ice compartment  22  takes place during the molding of the fresh food compartment liner  110 . The liner  110  is formed in a conventional manner from a flat sheet of material using male and female molds  112 ,  114 , as seen in  FIGS. 36 and 37 . The sheet material is heated and then placed between the open molds  112 ,  114 , which are then closed in a vacuum box. Simultaneously, a three-dimensional plug  116  is moved in a direction opposite the male mold  112  so as to deform the sheet material from the rear side opposite the male mold  112 . Alternatively, the plug  116  can be stationary and the liner  110  formed around the plug  116 . The plug  116  forms a notch  117  in an upper corner of the liner  110 . The notch  117  defines an outer shell  118  of the ice compartment  22 . Thus, the outer shell  118  is integrally formed with the liner  110  of the fresh food compartment  12 . After the liner  110  and the outer shell  118  are completely formed, the plug  116  is withdrawn and the male mold  112  is separated from the female mold  114 . The liner  110  with the outer shell  118  of the ice compartment  22  is then removed and cooled. The front wall of the outer shell  118  is punched or cut so as to form an opening  120 . A second hole  121  is punched or cut in the shell  118  for the air vent  44 . The liner  112  is then moved to a punch station to trim the edges of the liner  110 . 
     The ice compartment  22  includes a box  122  which is inserted through the front opening  120  into the outer shell  118  so as to define an inner shell. The space between the outer shell  118  and the box or inner shell  122  is filled with an insulating foam, such that the ice compartment  22  is insulated. This insulation process may take place at the same time that insulation is applied between the liner  110  and the outer cabinet of the refrigerator  10 . The ice box  122  includes a rear hole  123  for connection to the cold air duct  30 , a second rear hole  125  for connection to the return air duct  38 , and a side hole  127  for the vent opening  44 . 
     Modular Icemaking Compartment 
     As an alternative to an icemaking compartment formed integrally in the liner  110 , the compartment  22  can be formed separately and then attached to the liner. This modular compartment is shown in  FIGS. 38 and 39 , and includes the liner  110 A of the fresh food compartment, and the ice box  122 A, which preferably is insulated. All other features and components of the compartment  22  are the same, other than how it is made. The modular unit can be mounted anywhere in the fresh food compartment  12 . 
     Wire Harness 
     The ice compartment  22  is adapted to receive the icemaker  50 , which is mounted therein using any convenient means. The ice box  122  includes a recess  124  adapted to receive the wire harness  126  for the icemaker  50 . The wire harness  126  may be adapted to allow for connection to the icemaker  50  prior to complete insertion or mounting of the ice maker  50  into the compartment  12 . For example, the wire harness  126  may be adapted to be operatively connected to the refrigerator near the front portion of ice box  122  to allow for sufficient travel of the ice maker upon insertion or mounting of the ice maker  50 . The wire harness  126  is operatively connected at the rearward portion of ice maker  50 . In this case, an assembler may connect the wire harness  126  to the ice maker  50  and/or the refrigerator prior to fully inserting or mounting ice maker  50  into ice box  122 . 
     A cover  128  may be provided for the wire harness recess  124  so as to enclose the wire harness  126  prior to connecting the harness  126  to the icemaker  50 . The ice box  122  has a hole  129  in a side wall to mount the connector or clip of the wire harness. 
     Ice Bin Assembly 
     The ice compartment  22  also includes an ice bin assembly  130 . The assembly  130  is removable for assembly, service, and user access to bulk ice storage. The components of the bin assembly  130  are shown in  FIGS. 22 and 23 . The bin assembly  130  includes a tray or bin  132  for receiving ice from the icemaker  50 . An auger  134  is mounted within the tray  132 , with the first end  136  of the auger  134  being received in a motor  138  which is mounted in the upstream end  140  of the tray  132 . The second end  142  of the auger  134  is mounted in a housing  144  on a front plate  146  of the bin assembly  130 . A short piece of auger flighting  143  is provided on the second end  142  of the auger  134 , within the housing  144 . The housing  144  includes an outlet opening  148 , with a flipper door  150  in the housing  144  to control opening and closing of the outlet opening  148 . The flipper door  150  is mounted upon a shaft  152  extending through the tray  132 . A spring  154  mounted on the shaft  152  engages the flipper door  150  to normally bias the door  150  to a closed position over the outlet opening  148 . The shaft  152  can be turned by a solenoid (not shown) so as to move the flipper door  150  to an open position relative to the outlet opening  148 , such that ice can be discharged from the tray  132  to the dispenser  20 . 
     Front Cover Seal 
     A two-piece front cover  162  is provided on the bin assembly  130 . A front cover  162  includes an inner panel  164  and an outer panel  166 , as best seen in  FIG. 23 . Insulation is provided between the inner and outer panels  164 ,  166 , such that the front cover  162  is insulated. The inner panel  164  mounts onto the front plate  146  of the bin assembly  130 . A seal or compressible gasket  168  ( FIG. 24 ) is provided around the outer perimeter front plate  146  so that when the bin assembly  130  is installed into the ice box  122 , an air-tight seal is provided between the bin assembly  130  and the front opening  120  of the ice compartment  22 . The seal  168  helps maintain the lower temperature of the icemaking compartment  22 , as compared to the higher temperature of the fresh food compartment  12 . 
     The front cover  162  includes a latch mechanism for releasably locking the cover  162  to the ice compartment  22 . The latch mechanism includes a lock bar  170  extending through a pair of collars  172  on the front plate  146  of the bin assembly  130  for lateral sliding movement between a locked and unlocked position. The lock bar  170  is normally biased to the locked position by a spring  174 . A cam  176  is mounted on a peg  178  on the front plate  146  of the bin assembly  130  and is adapted to engage a flange or finger  180  on the end of the lock bar  170 . The cam  176  overcomes the bias of the spring  74  when actuated by a finger button  182  mounted on the outer panel  166 , so as to release the front cover  162  for removal of the bin assembly  130 . Thus, the bin assembly  130  can be slid into the ice box  122  and retained with an air-tight seal to maintain the temperature of the ice compartment  22 . A user can depress the button  182  on the bin assembly  130  to release the lock bar  170  for removal of the bin assembly  130  from the ice box  122 . 
     Air Impingement 
     Another component of the icemaker  50  is an air impingement assembly  190 , as shown in  FIGS. 33-35 . The impingement assembly  190  includes a manifold  192  and a bottom plate  194  which define an air plenum therebetween. The manifold  192  includes a plurality of holes or nozzles  196 . The manifold  192  is operatively connected to the cold air duct  30  so the cold air from the freezer compartment  14  is directed into the manifold  192  by the fan  36 , and through the impingement nozzles  196  onto the bottom of the mold of the icemaker  50 , as best seen in  FIG. 34 . 
     The nozzles  196  are shown to be round, but may also be slotted, or any other shape. The nozzles  196  are preferably arranged in staggered rows. The diameter of the nozzles  196 , the spacing between the nozzles  196 , and the distance between the nozzles  196  and the ice mold are optimally designed to obtain the largest heat transfer coefficient for a prescribed air flow rate. For example, in a preferred embodiment, the nozzles  196  are round with a diameter of 0.2-0.25 inches, with a spacing of approximately 1.5 inches between adjacent nozzles, and a distance of 0.5-1.0 inches from the surface of the icemaker  50 . The alignment of the nozzles  196  with the ice mold preferably avoids direct air impingement on the first two ice cube slots near the icemaker thermostat so as to avoid hollow ice production. 
     The air impingement assembly  190  speeds ice production by 2-3 times so as to meet large requirements of ices The impingement assembly  190  is also compact so as to permit increased ice storage space in a larger sized tray  132 . 
     Bale Plate 
     The ice maker  50  includes a bale plate  198  which shuts off the ice maker  50  when the level of ice cubes in the tray  132  reaches a pre-determined level. The plate  198  is pivotally connected to the ice maker  50  by a connector  200  at one end of the plate  198 , as seen in  FIG. 35 . The plate  198  pivots in a vertical plane. The plate  198  is stronger than a conventional wire bale arm. The vertical orientation of the plate  198  prevents ice from hanging up on the plate, which happens with a wire bale arm. The plate includes a plurality of holes  202  to reduce weight and to improve air flow. 
     Water Valve and Tank Assembly 
     Prior art refrigerators with water and ice dispensers typically locate the water system components, such as tanks, valves, filter and tubing, throughout the refrigerator cabinet and base pan areas. This arrangement is prone to service calls to repair leaks and water restrictions due to the larger number of connections or fittings for the components. The multiple connections and various tubing lengths also add to manufacturing costs. 
     In the present invention, the water system is pre-assembled in a single module that can be quickly and easily installed. The module has less tubing runs and connections between components as compared to prior art water systems. 
     The fresh food compartment  12  includes a recess or cavity  210  in the rear wall adapted to receive a water valve and tank assembly  212 . The water valve and tank assembly  212  is shown in  FIGS. 28 and 29 . The assembly  212  includes a mounting bracket  214  which is secured in the recess  212  in the back wall of the fresh food compartment  12  in any convenient manner. A water tank  216  is mounted on the bracket  214  and includes a water inlet line  218  and a water outlet line  220 . A cover  222  attaches to the rear wall of the fresh food compartment  12  so as to hide the water tank  216  from view when the door  16  of the fresh food compartment  12  is opened. 
     The water inlet line  218  is connected to a conventional water supply line. The water outlet line  220  is operatively connected to a filter  224 . Preferably, the filter  224  is pivotally mounted in the ceiling of the fresh food compartment  12 , as disclosed in Applicant&#39;s co-pending application Ser. No. 10/195,659, entitled HINGE DOWN REFRIGERATOR WATER FILTER, filed Jul. 15, 2002, which is incorporated herein by reference. 
     The water filter  220  has an outlet line  226  which is connected to a water solenoid valve  228  mounted on the bracket  214 . The valve  228  has a first outlet line  230  leading to the icemaker fill tube  232  and a second outlet line  234  leading to the water dispenser of the refrigerator  10 . Line  234  has a fitting  236  which provides a quick connection with a simple ¼ turn, without threads to the water dispenser line in the door  16 . 
     In prior art refrigerators, the water tank is normally located downstream of the water valve and filter, so as to prevent subjecting the water tank to inlet water supply pressures. In this invention, the tank  216  is designed to withstand inlet water supply pressures. The location of the tank  216  in the recess  210  allows greater fresh food storage capacity. Also, the location of the tank  216  upstream from the filter  224  and the valve  228  will reduce the service call rate. The downstream location of the filter  224  also removes plastic tastes associated with the plastic tank  216 , and allows chlorinated water to be stored in the tank  216 , which prevents microbiological growth on the interior of the water tank  216 . 
     Water Fill Tube 
     Prior art icemaker fill tubes are normally installed in the back of a freezer and run down a sloping tube to the icemaker. As seen in  FIGS. 30-32 , in the present invention the water fill tube  232  for the icemaker  50  extends downwardly through a vertically disposed hole  236  in the top wall  238  of the refrigerator  10 . The fill tube  232  is installed from the top of the refrigerator  10  into a plastic cup  244  positioned within a recess  246  in the top wall  238 . The fill tube  232  extends through the insulation in the top wall  238  and into the icemaker  50  in the icemaking compartment  22 . The water conduit  230  extends through the foam insulation in the top wall  238  and through an opening  248  in the cup  244  for connection to a nipple  250  on the fill tube  232 . The nipple  250  is angled slightly upwardly to prevent dripping. The cup  238  is open at the top so as to expose the fill tube  232  to the ambient air, and thereby prevent freeze-up of the fill tube  232 . This vertical orientation allows the fill tube  232  to be positioned closer to the end of the icemaker  50 . 
     Control System Details 
     The control system of a preferred embodiment of a bottom mount refrigerator with an ice compartment is now described in greater detail. It is to be understood, however, that many of the inventive features of the control system have utility beyond use in conjunction with a bottom mount refrigerator with an ice compartment, and in fact, such features can be used in refrigerators of more conventional design. Thus, what is specifically disclosed herein is not to be unduly limited to any specific embodiment of a refrigerator. 
       FIG. 40A  illustrates one embodiment of a control system of the present invention suitable for use in a refrigerator having three refrigerated compartments, namely the freezer compartment, the fresh food compartment, and the ice making compartment. The three compartments are preferably able to be set by the user to prescribed set temperatures. 
     In  FIG. 40A , a control system  510  includes an intelligent control  512  which functions as a main controller. The present invention contemplates that the control system  510  can include a plurality of networked or otherwise connected microcontrollers. The intelligent control  512  can be a microcontroller, microprocessor, or other type of intelligent control. 
     Inputs into the intelligent control  512  are generally shown on the left side and outputs from the intelligent control  512  are generally shown on the right side. Circuitry such as relays, transistor switches, and other interface circuitry is not shown, but would be apparent to one skilled in the art based on the requirements of the particular intelligent control used and the particular devices being interfaced with the intelligent control. The intelligent control  512  is electrically connected to a defrost heater  514  and provides for turning the defrost heater on or off. The intelligent control  512  is also electrically connected to a compressor  516  and provides for turning the compressor  516  on or off. The intelligent control  512  is also electrically connected to a damper  518  and provides for opening or closing the damper  518 . The intelligent control  512  is also electrically connected to an evaporator fan  520  associated with the freezer compartment and provides for controlling the speed of the evaporator fan  520 . Of course, this includes setting the evaporation fan  520  to a speed of zero which is the same as turning the evaporator fan  520  off. The use of a variable speed fan control is advantageous as in the preferred embodiment, the fan is serving an increased number of compartments with more states (freezer, fresh food, ice maker) and the ice compartment is remote from the freezer compartment. 
     The intelligent control  512  is electrically connected to an ice box fan  522  and provides for controlling the speed of the ice box fan  522 . Of course, this includes setting the ice box fan  522  to a speed of zero which is the same as turning the ice box fan  522  off. The intelligent control  512  also receives state information regarding a plurality of inputs. For example, the intelligent control  512  has a damper state input  530  for monitoring the state of the damper. The intelligent control  512  also has a defrost state input  532  for monitoring the state of the defrost. The intelligent control  512  also has a freezer door input  534  for monitoring whether the freezer door is open or closed. The intelligent control  512  also has a fresh food compartment door input  536  for monitoring whether the fresh food compartment door is open or closed. The intelligent control  512  also has an ice maker state input  538  for monitoring the state of the ice maker. The intelligent control  512  has a freezer set point input  540  for determining the temperature at which the freezer is set by a user. The intelligent control  512  also has an ice maker set point input  539 . The intelligent control  512  also has a fresh food compartment set point input  542  for determining the temperature at which the fresh food compartment is set by a user. The intelligent control  512  is also electrically connected to four temperature sensors. Thus, the intelligent control  512  has an ice maker temperature input  544 , a freezer compartment temperature input  546 , a fresh food compartment input  548 , and an ambient temperature input  550 . The use of four separate temperature inputs is used to assist in providing improved control over refrigerator functions and increased energy efficiency. It is observed that the use of four temperature sensors allows the ice maker temperature, freezer compartment temperature, fresh food compartment temperature, and ambient temperature to all be independently monitored. Thus, for example, temperature of the ice box which is located remotely from the freezer can be independently monitored. 
     The intelligent control  510  is also electrically connected to a display control  528 , such as through a network interface. The display control  528  is also electrically connected to a mullion heater  524  to turn the mullion heater  524  on and off. Usually a refrigerator has a low wattage heater to supply heat to where freezing temperatures are not desired. Typically these heaters are 120 volt AC resistive wires. Due to the fact that these heaters are merely low wattage heaters, conventionally such heaters remain always on. The present invention uses a DC mullion heater and is adapted to control the DC mullion heater to improve overall energy efficiency of the refrigerator and increase safety. 
     The display control  528  is also electrically connected to a cavity heater  526  for turning the cavity heater  526  on and off. The display control  528  is preferably located within the door and is also associated with water and ice dispensement. Usually a refrigerator with a dispenser with a display on the door will also have an associated heater on the door in order to keep moisture away from the electronics of the dispenser. Conventionally, this heater is continuously on. 
     It is to be observed that the control system  510  has a number of inputs and outputs that are not of conventional design that are used in the control of the refrigerator. In addition, the control system  510  includes algorithms for monitoring and control of various algorithms. The algorithms used, preferably provide for increased efficiency while still maintaining appropriate temperatures in the ice maker, fresh food compartment, and freezer. 
       FIG. 40B  illustrates another embodiment of a control system of the present invention. The control system seeks to maintain a balance between optimum ice production and the requirements of the fresh food and freezer compartments. This is achieved via the following inputs operatively connected to the main  1400 : ambient temperature  1402 ; freezer compartment set point and instantaneous temperature  1404 ; fresh food compartment set point and instantaneous temperature  1406 ; ice making compartment set point and instantaneous temperature  1408 ; ice maker state  1410 ; ice storage compartment capacity  1412 ; initial refrigerator “power up” state  1414 ; and defrost state  1416 . These inputs are used to control the following outputs: ice maker  1418 ; fresh food damper  1420 ; ice making compartment set point  1422 ; water valve  1424 ; ice making compartment fan  1426 ; evaporator fan  1428 ; and compressor run time  1430 . 
     Based on the requirements of the system, these output functions are prioritized to seek the best solution to the heat removal rate for cooling/ice production systems as described below: 
     1. Multiple Pre-Set Non User-Adjustable Ice Making Compartment Set Points
         a. Set Point for Pull Down mode. This condition is met when the refrigerator is first turned on (new unit or if unit has been in storage). In this mode, the temperature inside of the ice making compartment is ignored for a pre-set length of time thus allowing maximum heat removal from the fresh food and subsequently results in it reaching of set point temperature more rapidly.   b. Set Point for Emergency or “Melt” modes. This condition is met when the ice making compartment warms above a predetermined maximum and seeks to maximize the heat removal rate.   c. Set Point for ice maker turned off mode. This condition is met when the ice maker is turned off and seeks to minimize the heat removal rate from the ice making compartment for optimum ice storage temperature.   d. Set Point for ice maker turned on mode. This condition is met when the ice maker is turned on and the ice storage bin is full. This condition seeks to minimize the heat removal rate when the bin is full and maximize it very quickly when the bin requests additional ice production (see item d).   e. Set Point for ice maker turned on mode. This condition is met when the ice maker is turned on and the ice storage bin requests additional ice production. In this mode, the heat removal rate is maximized which may or may not result in the ice making compartment temp being significantly less than the set point temperature.       

     2. Ice Storage Bin Full Based on Last Time of Harvest
         a. This condition is met when the ice maker is turned on. The control system keeps track of time beginning at the end of the last ice maker harvest. Based on this time interval, the control determines whether or not the ice bin still requesting additional ice production or is full. If the bin is full, the system changes from a maximum heat removal to a lesser rate thus allowing more heat removal from the freezer and fresh food compartments.       

     3. Ice Maker Harvest Mode
         a. This condition is met when the ice maker is on and the control system recognizes that the ice maker is beginning the harvest mode. Based on this information, the ice making compartment fan turns off and the fresh food damper opens. This operation stops the heat removal process in the ice making compartment and optimizes the ice maker harvest time. Additionally, by opening the fresh food damper, heat is removed from this compartment which optimizes its temperature.       

     4. Heat Removal Capacity in the Ice Making Mode
         a. This condition is met when the ice maker is on. In this mode, the control recognized the need for optimum heat removal from the ice making compartment. In this mode, the need for optimum heat removal rate is recognized which may or may not result in the freezer compartment temperature being significantly less than the set point temperature.   b. After the ice production mode is satisfied, the freezer heat removal rate returns to the non-ice production mode.       

     5. Multiple Speed For the Ice Making Compartment Fan Based on Fresh Food, Freezer, and Ice Making Compartment
         a. This condition is met when the ice maker is on or off. In this mode, the fan can run at two different speeds based on the requirement for ice production or ice storage:
           i. Ice production, temp set point a: Fan maintains optimizes speed for this requirement   ii. No requirement for ice, temp set point b: Fan optimizes speed for this requirement.   iii. No requirement for ice, temp set point c: Fan optimizes speed for this requirement.   iv. Ice making compartment “emergency mode”, temp set point d: Fan optimizes speed for this requirement.   
               

     6. Ice Making Compartment Fan Used to Cool the Fresh Food Compartment
         a. This condition is met when the ice maker is on or off. In this mode, the fresh food compartment is above the temperature set point. In this mode, the fresh food damper opens and the fan goes to optimum speed for the required heat removal rate. After the fresh food temperature set point is satisfied, the damper closes, and the fan returns to the optimum speed for heat removal rate in the ice making compartment. Note that this type of system eliminates the need for both a second fan and second damper for the fresh food compartment. This serves to greatly simplify the design of the associated air channels, component wiring, electronic hardware, and software.       

     The ice maker state affects the fresh food and freezer via the ice making compartment&#39;s heat removal rate requirement. There are three main states that the ice maker and system operate in: (1) the ice maker is turned off; (2) the ice maker is turned on and the ice storage area is requesting ice production; and (3) the ice maker is turned on and the ice storage area is not requesting ice production. 
     When the ice maker is turned off, the ice making compartment control selects the “ice storage” mode where the heat removal rate is optimized. This mode increases the heat removal capacity available for the other compartments. 
     The ice maker is turned on and the ice storage area is requesting ice production. The control system seeks to optimize the heat removal rate for ice production. This results in a high rate of heat removal in the ice making compartment and a reduced amount of heat removal capacity available for the other compartments. The end result is an increased compressor run time to cool the freezer and an increased air damper open period to cool the fresh food. 
     When the ice maker is turned on and the ice storage area is not requesting ice production, this results in a combination of low and high heat rate removals. The requirement is based on the ice storage area requesting ice production or not. 
     The ice maker state affects the damper and evaporator fan. During the harvest mode, when the ice maker begins its harvest cycle, the fresh food damper routes the supply air away from the ice maker and into the fresh food compartment. In addition, the evaporator fan continues to run which allows the control system to keep the compressor running. After the ice maker completes the ice harvest, the ice maker state affects the damper and evaporator fan. In particular, the fresh food damper closes and redirects the supply air for ice production and the evaporator fan continues to run. 
     Another aspect of the control system of the present invention provides for synchronization. 
     The methodology reduces or eliminates non-uniform temperature patterns and produces consistent power consumption patterns during non-transient usage in a chilling and/or freezing device with more than one compartment. 
     This is accomplished by making the logic controlling a slave chilled compartment a function of both the chilled compartment sensed temperature and primary chilled compartment cooling device (compressor state (ON/OFF)). Namely, when the compressor turns ON, the slave chilled compartment would also be cooled unless the slave chilled compartment temperature was lower than the lower temperature threshold (cut out). Likewise, when the compressor turns OFF, the slave chilled compartment would also stop cooling unless the slave chilled compartment temperature was higher than the upper temperature threshold (cut in). The slave chilled compartment would eventually be synchronized with the compressor cycles, so that every compartment employing this algorithm would attempt to cool down during the time when the compressor is on. 
       FIGS. 41-54  provide an exemplary embodiment of the present invention showing how the control system sets the states and controls refrigerator functions based on those states, including states associated with the fresh food compartment, freezer compartment, and ice maker compartment.  FIG. 41  is a flow diagram providing an overview of one embodiment of the present invention. In  FIG. 41 , an executive loop  560  is shown. In step  562  a determination is made as to whether a set time period (such as 30 seconds) has elapsed. If so, then a set of steps  564  are performed to update state variables. These state variables are updated through a calculate temperatures subroutine  566 , an adjust setpoints subroutine  568 , an update freezer subroutine  570 , an update ice box subroutine  572 , an update fresh food compartment subroutine  574 , an update defrost subroutine  576 , a check stable cycles routine  580 , and a scan ice maker subroutine  582 . Once the state variables are updated, then there are a set of control subroutines  566  which act on the state variables. These control routines include a control compressor subroutine  584 , a control damper subroutine  586 , a control evaporator fan subroutine  588 , a control ice box fan subroutine  590 , and a control defrost heater subroutine  592 . 
     As shown in  FIG. 41  the status of the state variables are regularly updated in the set of steps  564 . After the state variables are updated, appropriate actions are performed to control refrigerator functions. 
     The calculate temperatures subroutine  566  is shown in greater detail in  FIG. 42 . In one embodiment, each compartment&#39;s temperature and the ambient temperature are measured with thermistors to provide raw data. Regressed temperatures are calculated based in part on the raw temperatures. 
     According to one embodiment of the present invention, a mathematic regression method is used to calculate the desired performance temperatures in each compartment using a single temperature sensing device in each compartment resulting in a correlation. The sensing device is located in a way that is preferred or reasonable for product assembly requirements, but the correlation allows the control to evaluate the product performance considering the approximated performance temperatures in each compartment. The approximated performance temperatures are developed based on the criteria that would be considered by a typical consumer: the average temperatures of multiple locations throughout a compartment. The correlation can further be mathematically manipulated to represent a variety of food stuffs of various mass and density. This allows the control to react in a manner that optimizes the food preservation function for food stuff types stored in each designated compartment type. 
     The correlation is arrived at by testing product in variety of environments and usage conditions monitoring the temperatures at the sensor locations and multiple other locations in each compartment and all other compartments simultaneously. Other thermal in influences such as ambient conditions or machine compartment conditions may also be included. A mathematic correlation is then calculated determining the best fit for each temperature sensor location using some or all of the significant contributing measurements made from the multiple locations of interest in the correlated compartment and the temperature sensing locations used in other compartments. Correlations from a first compartment may be used as contributing factors in other compartments completing a system correlation. 
     The correlations may be mathematically weighted by considering the most recent value calculated or measured as only a fraction of the full running weighted value for a given compartment temperature. In fact multiple weighting values may be calculated to achieve different approximations of temperatures associated with food stuffs due to varied mass and densities. Additional weighting values may be desirable for other functions such as displayed temperature, other correlations, special performance modes, or historical average data storage. 
     The present invention uses these correlations and weighting concepts in three compartments using four specific sensor locations. Some or all of these temperature locations, their compartment correlations, and some correlations or sensor readings and weighting of the associated values are used to calculate the performance temperatures for each compartment. A freezer sensor is located on the back side of the evaporator cover. A refrigerator sensor is located inside the fresh food light housing assembly on the upper fresh food liner surface. An ice box sensor is located in the rear of the ice making compartment. An ambient temperature sensor is located behind the dispenser user interface face plate. These system sensors, correlations, and weights are used to improve product performance in a variety of ambient conditions. They are used to improve temperature stability and food preservation. They are also used to improve energy performance and product diagnostics. 
     In step  1300  of the method  566  of  FIG. 42 , temperatures are calculated and raw temperatures are read from each of four temperature sensors—one in the fresh food compartment (FFRaw), one on the freezer (FZRaw), one for providing an ambient temperature (AMRaw), and one associated with an icemaker (ICRaw). In step  1304 , a determination is made as to whether or not this is the first pass through the algorithm. If it is, then in step  1306  value AMEffect is set to AMRaw, FZEffect is set to FZRaw, FFEffect is set to FFRaw, and ICEffect is set to ICRaw. In step  1308 , the ambient temperature is regressed to provide AMRegressed. Note that a weighting (amcalc-am-wt) and an offset (am calc-offset) are used. Step  1310  determines if this is the first pass. If it is, then in step  1312 , AMControl is set to AMRegressed and AMEffect is set to AMRegressed for initialization purposes. Returning to step  1310 , if it is not the first pass, then in step  1314 , AMControl is set based on the current value of AMControl, AMRegressed, and a constant am ctl_K. Then in step  1316 , AMEffect is set based on the current value of AMEffect, AMControl, and a constant, ameff_K. 
     Next, in step  1318 , a regressed temperature for the freezer, FZRegressed, is calculated based on weighting (fzcalc_fz_wt, fzcalc_ff_wt, fzcalc_am_wt) of a temperature associated with the freezer (FZRaw), the effective fresh food temperature (FFEffect) and the effective ambient temperature (AMEffect). An offset (fzcalc_offset) and an adjustment (FZAdjustment) are used in calculating the regressed temperature for the freezer. 
     In step  1320 , a determination is made as to whether this is the first pass. If it is, then FZControl, FZEffect, and FZDisplay temperatures are set to the regressed temperature (FZRegressed). If this is not the first pass, then in step  1324 , a freezer control temperature (FZControl) is set based on the current FZControl, FZRegressed and a constant, fzctl_K. Then in step  1326 , FZEffect is calculated based on the current FZEffect, FZControl, and a constant, fzeff_K. 
     Temperatures associated with the fresh food compartment are calculated in steps  1328 ,  1330 ,  1332 ,  1334 , and  1336  in a manner similar to those of the freezer compartment. Similarly temperatures associated with the ice maker compartment are calculated in steps  1338 ,  1340 ,  1342 , and  1348 . Display temperatures are calculated in step  1348  and the algorithm and in step  1350 . 
       FIG. 43  illustrates a flow diagram for the adjust setpoints subroutine  568 . The user selects set points for the fresh food compartment (FFSetpoint) and the freezer compartment (FZSetpoint). Based on the user settings, or other settings if a food saver feature is active (ff_saver_setpoint, fz_saver_setpoint), an ice maker set point (ICSetpoint) is set. Under default conditions (DEFAULT) the ice maker set point (ICSetpoint) is the same as the freezer set point (FZSetpoint). If the ice maker&#39;s bin is full (BIN_FULL), then the ice maker&#39;s set point (ICSetpoint) is set at a lower temperature to maintain the ice and prevent melting. If the ice maker is turned off, then the ice maker&#39;s set point is set at a higher temperature (ICE_EFF) thereby providing an efficiency mode to thereby conserve energy. For example, it is generally expected that the ice maker&#39;s set point for storage (ICE_STORE) is less than the ice maker&#39;s temperature when the power is off such as in an energy efficient mode of operation (ICE_EFF), which is less than the temperature required to melt ice. For example, the ice storage temperature (ICE_STORE) may be around 15 degrees Fahrenheit while the ice maker&#39;s efficiency temperature (ICE_EFF) is 25 degrees. Ice might begin to melt at a temperature of 28 degrees Fahrenheit. 
     Thus, in step  602  a determination is made as to whether the food saver function is active. If it is, then in step  604 , the set point for the fresh food compartment (FFSetpoint) is set accordingly to ff_saver_setpoint. Also, the set point for the freezer compartment (FZSetpoint) is set accordingly to fz_saver_setpoint and then the subroutine proceeds to select the ice maker state in step  608 . Returning to step  602 , if the food saver function is not active, then in step  606 , the fresh food set point (FFSetpoint) is set to a user selected temperature setting and the freezer set point (FZSetpoint) is set to a user selected temperature setting. 
     In step  608 , the ice maker state is selected. If the ice maker state is turned off (PWR_OFF) to conserve energy, then the ice maker&#39;s set point (ICSetpoint) is set to an energy efficient temperature less than the melting point (ICE_EFF) in step  610 . If the ice maker state indicates that the ice bin is full (BIN_FULL) then the ice maker&#39;s set point (ICSetpoint) is set to an ice storage temperature (ICE_STORE) in step  612 . If the ice maker state is the default state (DEFAULT) then the ice maker&#39;s set point (ICSetpoint) is set to the freezer set point (FZSetpoint). 
       FIG. 44A  is a flow diagram illustrating one embodiment of the update freezer subroutine  570 . The update freezer subroutine assists in increasing the energy efficiency of the appliance because instead of merely turning on the freezer when temperature reaches a particular setpoint, the update freezer subroutine also considers the states of the fresh food compartment and ice maker and how ultimately temperature will be affected over time. The update freezer routing is used to set states associated with the freezer, fresh food compartment and ice maker. In step  622  the fz_adj_cuts state is determined. If true then in step  630 , the threshold is set to the freezer set point (FZSetpoint). If in step  622 , the fz_adj_cuts state is not true, then in step  628 , the freezer cut-in temperature (FZCutIn) is set to fz_cutin and the freezer cut-out temperature is set to fz_cutout. Then in step  630 , the threshold is set to the freezer set point (FZSetpoint). 
     In step  632  a determination is made as to whether the refrigerator state (FridgeState) is set to a sub-cool state (SUBCOOL). If it is, then in step  638 , the Threshold is set to the difference of the Threshold and the subcool_depression. Then in step  640 , a determination is made as to whether the freezer is in the freezer cooling (FZCooling state). If it is, then in step  642 , the Threshold is set to be the difference between the Threshold and the freezer cut-out temperature (FZCutOut). Then in step  652 , a determination is made whether the freezer control temperature (FZControl) is less than or equal to the threshold temperature (Threshold). If it is, then in step  654 , the freezer cooling condition (FZCooling) is set to be FALSE and the first cut-out temperature, CO( 1 ), is set to the difference of the freezer setpoint (FZSetpoint) and the freezer control temperature (FZControl). Next in step  662 , a determination is made as to whether the synchronize fresh food compartment with freezer (sync_ff_with_fz) or fresh food adjust cuts (ff_adj_cuts_states are TRUE. If one of these states are true, then in step  660 , the fresh food cooling state (FFCooling) is set to be FALSE. If, however, neither of these states are true, in step  670 , a determination is made as to whether the synchronize ice maker with freezer (sync_ic_with_fz) or ice maker adjust cuts (ic_adj_cuts) states are true. If one of these states is true, then in step  668 , the ice maker cooling state (ICCooling) is set to FALSE. 
     Returning to step  650 , if the freezer cooling state (FZCooling) is not set, then in step  646 , the threshold (Threshold) is set to be the sum of the threshold (Threshold) and the freezer cut-in temperature (FZCutin). Then in step  648 , a determination is made as to whether the threshold (Threshold) is greater than the sum of freezer&#39;s maximum set point (fz_max_setpoint) and the maximum freezer change (MAX_FZ_DELTA) divided by two. If it is, then in step  650 , the threshold (Threshold) is set to be the sum of the freezer&#39;s maximum set point (fz_max_setpoint) and the maximum freezer change (MAX_FZ_DELTA) divided by two. Then in step  654  a determination is made as to whether the freezer control temperature (FZControl) is greater than or equal to the threshold (Threshold). If it is, then in step  656  the freezer cooling state (FZCooling) is set to be TRUE. Then in step  658 , the Update Freezer Cuts subroutine is executed. Next in step  664 , a determination is made as to whether the synchronize fresh food compartment with the freezer compartment state (sync_ff_with_fz) or the fresh food adjust cuts state (ff_adj_cuts) state is true. If it is, then in step  666  the fresh food cooling state (FFCooling) is set to be true. Then in step  672 , a determination is made as to whether the synchronize ice maker with freezer state (sync_ic_with_fz) or the ice maker adjust cuts (ic_adj_cuts) states are true. If they are, then in step  674 , the ice maker cooling state (ICCooling) is set to be true. 
       FIG. 44B  provides an illustration of one algorithm for an update freezer cuts subroutine. Generally, the present invention provides for adjusting cuts through an algorithm which improves energy efficiency of a compartment(s) cooling system and improves temperature control of chilled compartment(s) to a desired average temperature (set-point). 
     This is accomplished by:
     (1) Adjusting the temperature thresholds of an on/off cooling system to produce a repeating cyclic pattern of control at a desired frequency. Namely, when a cooling system has operated in a stable pattern for a length of time as to be thought of as non-transient operation the algorithm will widen or compress the delta between the thresholds periodically to target a pre-determined frequency of on/off for the cooling system. The system is protected from affecting the thresholds adversely by limiting the change to between max and min deltas specified by the algorithm.   (2) Adjusting the temperature thresholds of an on/off cooling system to produce a repeating cyclic pattern of control about a desired average temperature (set-point). Namely when a cooling system has operated in a stable pattern for a length of time as to be thought of as non-transient operation, the algorithm will shift both the upper and lower thresholds as to target the calculated average of the last stored cycle and the set-point to be equal. The system is protected from affecting the thresholds adversely by limiting the magnitude of the change for each adjustment made.   

       FIG. 44B  is a flow diagram illustrating one embodiment of the update freezer cuts subroutine  658 . In step  680 , the cut-in temperatures are updated by setting the second cut-in temperature, CI( 2 ), to be equal to the first cut-in temperature, CI( 1 ). The first cut-in temperature, CI( 1 ), is then set to be equal to the difference of the freezer control temperature (FZControl) and the freezer setpoint (FZSetpoint). Also the stable cycles variable (StableCylces) is incremented. Next in step  682 , the cycle times are updated by setting the second cycle time, CT( 2 ), to be equal to the first cycle time, CT( 1 ). The first cycle time, CT( 1 ), is then set to the current cycle time. The average cycle time (CTavg) is then computed as the average of the first cycle time, CT( 1 ), and the second cycle time, CT( 2 ). The CT 0  is set to be target cycle minutes (target_cycle_minutes). 
     Next in step  686 , a determination is made as to whether the freezer adjust cuts state (fz_adj_cuts) is true. If it is, then in step  688 , a determination is made as to whether there are more than three stable cycles (StableCycles). If there are, then in step  690 , the desired delta is calculated from the deltas and the cut-out temperatures as shown. The bounds of the calculated desired delta are then checked in steps  692 - 698 . In step  692 , a determination is made as to whether Δ( 0 ) is less than the minimum freezer delta (MIN_FZ_DELTA). If it is, then in step  694 , Δ( 0 ) is set to be the minimum freezer delta (MIN_FZ_DELTA). If it is not, then in step  696 , a determination is made as to whether Δ( 0 ) is greater than the maximum freezer delta (MAX_FZ_DELTA). If it is, then in step  698 , Δ( 0 ) is set to be the maximum freezer delta (MAX_FZ_DELTA). In step  704 , the desired freezer cut-out temperature (FZCutOut) and the desired freezer cut-in temperature (FZCutIn) are set. 
     Then in step  684 , the deltas are updated accordingly. In particular, Δ( 2 ) is set to Δ( 1 ). Also, Δ( 1 ) is set to be the sum of the average of CI( 1 ) and CI( 2 ) and CO( 1 ). Also, Δavg is set to be the average of Δ( 1 ) and Δ( 2 ). 
       FIG. 44C  shows the relationship between the cooling state or flag  712 , and the control temperature  708  over time. Note that at point  716 , CI( 1 ), the cooling state of flag  712  cuts in, at point  714 , CI( 2 ), the cooling state or flag also cuts in, at point  718 , CO( 1 ), the cooling state or flag cuts out. For cycle CT( 1 )  722  there is an associated average control temperature (Tavg) and for cycle CT( 2 )  720  there is an associated average control temperature (Tavg). 
       FIG. 45A  illustrate one embodiment of the update ice box subroutine  572 . In  FIG. 45A , a determination is made in step  730  as to whether the icemaker adjust cuts state (ic_adj_cuts) is true. If not, then in step  734 , the ice maker cut in time (ICCutIn) and the ice maker cut out (ICCutOut) times are set. Then in step  738 , the threshold (Threshold) is set to the ice maker set point (ICSetpoint). Next, in step  740 , a determination is made as to whether the ice maker cooling state (ICCooling) is set. If not, then in step  746 , a determination is made as to whether the freezer cooling state (FZCooling) is set. If not, then in step  743 , a determination is made as to whether the synchronize ice maker with freezer state (sync_ic_with_fz) is set. If it is, then in step  744 , the threshold (Threshold) is set to the sum of the Threshold and the ice maker cut-in adjustment value (IC_CI_ADJ). In step  748 , the threshold (Threshold) is set to be the sum of the threshold (Threshold) and the ice maker cut in (ICCutIn). Next in step  752 , the upper bound for the threshold is tested and if the bound is exceeded, in step  756 , the threshold is set to be the upper bound. Next in step  754 , a determination is made as to whether the ice maker control (ICControl) is greater or equal to the threshold. If it is, then in step  762 , the ice maker cooling state is set to true. 
     Returning to step  740 , if the ice maker cooling state is true, then in step  750 , the threshold is set to the difference of the threshold and the ice maker cutout. Then in step  758 , the ice maker cooling state is set to be false. 
     In step  764  a determination is made as to whether the ice maker was previously in a cooling state. If not, then in step  766  a determination is made as to whether the ice maker cooling state is true. If not, then the first cut-out time, CO( 1 ) is set to be the difference between the ice maker setpoint (ICSetpoint) and the ice maker control (ICControl). If it is, then in step  772 , an update ice box cuts subroutine is executed. In step  770 , the previous ice maker cooling stat (ICCoolPrev) is set to cooling (ICCooling). 
       FIG. 45B  illustrates the ice box cuts subroutine  772 . In step  780 , the cut-ins are updated. In step  782  the deltas are updated. In step  784 , a determination is made as to whether the ice_adj_cuts state is true. If it is, then in step  786  a determination is made as to whether there have been at least three stable cycles. If so, in steps  788 ,  790 ,  792 , and  794 , the boundaries of Δ 0  are tested. In step  796  the desired cuts are calculated. 
       FIG. 45C  shows the relationship between the cooling state or flag  800 , and the control temperature  814  over time. Note that at point  812 , CI( 1 ), the cooling state of flag  800  cuts in, at point  816 , CI( 2 ), the cooling state or flag also cuts in, at point  822 , CO( 1 ), the cooling state or flag cuts out. For cycle CT( 1 )  818  there is an associated average control temperature (Tavg) and for cycle CT( 2 )  820  there is an associated average control temperature (Tavg). 
       FIG. 46A  illustrates one embodiment of a flow diagram for the update fresh food subroutine  574 . In  FIG. 46A , a determination is made as to whether the ice maker state (IMState) is melting. If it is, then in step  858 , the fresh food compartment cooling state is set to false. If it is not, then in step  856  a determination is made as to whether the freezer cooling state (FZCooling) is true. If it is not then in step  858  the fresh food compartment cooling (FFCooling) state is set to false. If the freezer cooling (FZCooling) state is true, then in step  860 , a determination is made as to whether the ff_adj_cuts state is true. If it is not, then in step  866  values for the fresh food cut-in and cut-out values are set accordingly. In step  868 , the threshold (Threshold) is set to the fresh food compartment setpoint. In step  870 , a determination is made as to whether the fresh food cooling (FFCooling) state is true. If not in the fresh food cooling (FFCooling) state, then in step  872 , a determination is made as to whether the freezer cooling state is true. If it is then, the threshold is set in step  878 . If it is not, then in step  874  a decision is made as to whether the threshold needs to be adjusted to compensate for the synchronization state. If it does not then, in steps  876  and  878  the threshold is adjusted accordingly. Then in step  880  a determination is made as to whether the fresh food compartment temperature is greater than or equal to the threshold. If it is, then in step  882 , the fresh food cooling state (FFCooling) is set to be true. 
     Returning to step  870 , if the fresh food compartment cooling (FFCooling) state is true, then the threshold is modified in step  884 . In step  886  a determination is made as to whether the threshold is less than the difference of the fresh food compartment&#39;s minimum setpoint and half of the maximum fresh food compartment change. If it is, then in step  890 , the threshold is set to the difference of the fresh food compartment&#39;s minimum setpoint and half of the maximum fresh food compartment change. Then in step  888  a determination is made as to whether the fresh food compartment control temperature is less than or equal to a threshold. If it is then the fresh food cooling state (FFCooling) is set to be false. In step  894 , the fresh food cooling&#39;s previous state (FFCoolPrev) is compared to the present fresh good cooling (FFCooling). If they are not equal, then in step  896 , a determination is made as to whether the fresh food cooling (FFCooling) state is true. If it is then, an Update Fresh Food Cuts subroutine  898  is run to update cut-in and cut-out temperatures. If it is not then the cutout temperature, CO( 1 ), is set to be the difference between the fresh food setpoint (FFSetpoint) and the fresh food control setting (FFControl). Then in step  900  the previous fresh food cooling state (FFCoolPrev) is updated to the current fresh food cooling state. 
       FIG. 46B  illustrates one embodiment of a flow diagram for the update fresh food cuts subroutine  898 . In step  910  the cut-in temperatures are updated. In step  912 , the deltas are updated. In step  914 , a determination is made as to whether the fresh food compartment cut-in and cut-out temperatures need adjustment. If they do, in step  916  a determination is made as to whether there has been more than three consecutive stable cycles. If there has, then in steps  918 ,  920 ,  922 , and  924 , the delta is recalculated. In step  930  the cut-in and cut-out temperatures for the fresh food compartment are adjusted accordingly. 
       FIG. 46C  illustrates relationships between the cooling flag, control, temperature, setpoint, cut-ins, cut-outs, and cycle time for the update fresh food cuts subroutine.  FIG. 46C  shows the relationship between the cooling state or flag  932 , and the control temperature  934  over time. Note that at point  936 , CI( 1 ), the cooling state of flag  932  cuts in, at point  940 , CI( 2 ), the cooling state or flag also cuts in, at point  938 , CO( 1 ), the cooling state or flag cuts out. For cycle CT( 1 )  942  there is an associated average control temperature (Tavg) and for cycle CT( 2 )  944  there is an associated average control temperature (Tavg). 
       FIG. 47  illustrates one embodiment of a flow diagram for the update defrost subroutine  576 . In step  950  a determination is made as to whether to force a defrost. If a defrost is not forced, then in step  952  the refrigerator state is selected. If a defrost is forced, then in step  984  the defrost hold period is set, the refrigerator state is set to defrost and a flag for forcing a defrost is cleared. 
     Returning to step  952 , the refrigerator state can be COOL, SUBCOOL, WAIT, DEFROST, DRIP, or PULLDOWN. If the refrigerator state is cool, then in step  956  a determination is made as to whether defrost is due. If it is, then in step  960  the defrost timer is set and in step  965 , the freezer cooling (FZCooling) state is set to true and the refrigerator state is set to SUBCOOL. 
     Returning to step  952 , if the refrigerator is in the subcool state, then in step  966  a determination is made as to whether the defrost timer has expired. If it has, then in step  970 , the defrost timer is set and in step  976  the refrigerator state (FridgeState) is set to WAIT. If in step  966  the defrost timer has not expired, then in step  972  a determination is made as to whether the freezer is in the cooling state. If it is not, then in step  970  the defrost timer is set and in step  976  the refrigerator state (FridgeState) is set to WAIT. 
     Returning to step  952 , if the refrigerator state (FridgeState) is WAIT, then in step  978  a determination is made as to whether the defrost timer has expired. If it has, then in step  980  the defrost hold period is set and the refrigerator state is set to DEFROST. 
     Returning to step  952 , if the refrigerator state (FridgeState) is DEFROST, then in step  982 , a determination is made as to whether the defrost is complete. If it is then in step  984 , the defrost timer is set for time associated with dripping (drip_time), the refrigerator state (FridgeState) is set to DRIP and the flag associated with forcing defrost is cleared. 
     Returning to step  952 , if the refrigerator state (FridgeState) is DRIP, then in step  986 , a determination is made as to whether the defrost timer has expired. If it has, then in step  988 , the defrost timer is set and the refrigerator state is set to PULLDOWN. 
     Returning to step  980 , if the state is PULLDOWN, a determination is made as to whether or not the defrost timer has expired. If it has then in step  992 , the freezer cooling state (FZCooling) is set to true and the refrigerator state (FridgeState) is set to COOL. 
     In step  996 , a determination is made as to whether the refrigerator is in a DEFROST or COOL state. If it is, then the subroutine ends. If it is not, then in step  994  a determination is made as to whether the defrost timer has expired. If it has then the process returns to step  952 . If the defrost timer has not expired then the subroutine ends. 
       FIG. 48  illustrates one embodiment of a flow diagram for the check stable cycles subroutine  580 . The number of stable cycles is reset in step  1088  if in step  1080  the refrigerator is in the defrost state, in step  1082  the fresh food or freezer doors are open, in step  1084  the fresh food setpoint has changed, or in step  1086  the freezer setpoint has changed. 
       FIG. 49  illustrates one embodiment of a flow diagram for the scan ice maker subroutine  582 . This subroutine scans the ice maker to check for various conditions that may affect control functions and sets states associated with the ice maker appropriately. In step  1100  a determination is made as to whether the ice maker is in initial pulldown. If it is not, then in step  1102  a determination is made as to whether the ice maker control is above the melting temperature of ice. If it is then in state  1104 , the ice maker state is set to MELTING. If not, then in step  1106  a determination is made as to whether the fresh food compartment door is open. If it is, then in step  1108  the ice maker state is selected. If the ice maker state is MELTING, then in step  1110  the ice maker state is set to the previous ice maker state. If the ice maker state is set to HTR_ON then in step  1112  a determination is made as to whether the fresh food compartment door has been open for longer than a set dwell time. If it has, then in step  1110  the ice maker state is set to the previous ice maker state. If has not then in step  1114  the ice maker state remains unchanged. Similarly if the ice maker state is DEFAULT in step  1108  then the ice maker state remains unchanged in step  1114 . 
     In step  1116  a determination is made as to whether the ice maker power is on. If not, then in step  1118  the ice maker state and the ice maker&#39;s previous state are set accordingly to indicate that the power is off. In step  1120  a determination is made as to whether the ice maker&#39;s heater is on. If it is no then in step  1124  the ice maker&#39;s state is set to indicate that the heater is on. In step  1122  a determination is made as to whether the icemaker has been on less than a set dwell time. If it has, then in step  1124  the ice maker&#39;s state is set to indicate that the heater is on. 
     In step  1126  a determination is made has to whether the ice maker&#39;s heater has been on less than the amount of time associated with a full bin (such as 120 minutes). If it has then in step  1128  the ice maker&#39;s current state and previous state are set to indicate that the heater is off. If not, then in step  1130  the ice maker&#39;s current state and previous state are set to indicate that the bin is full. 
       FIG. 50  illustrates one embodiment of a flow diagram for the control compressor subroutine  584 . In step  1150  the refrigerator&#39;s state (FridgeState) is examined. If the refrigerator is in the COOL state, then in step  1152  a determination is made as to whether the freezer cooling state is true. If it is not, then in step  1154  a request is made to turn the compressor off. If it is, then a request is made in step  1156  to request that the compressor be on. If the state is SUBCOOL or PULLDOWN, then in step  1158  a request is made to turn the compressor on. If the state is DEFAULT, then in step  1160  a request is made to turn the compressor off. 
       FIG. 51  illustrates one embodiment of a flow diagram for the control damper subroutine  586 . In step  1170  the refrigerator state is selected. If the refrigerator state is COOL or SUBCOOL then in step  1172  the ice maker state is selected. IF the ice maker state is HTR_ON then in step  1174  a determination is made as to whether the evaporator fan is on. If it is then in step  1174  a request is made for the damper to be open. If not, then in step  1178  a request is made for the damper to be closed. If in step  1172  the icemaker state is MELTING&lt;then in step  1178  a request is made for the damper to be closed. If the ice maker is in a different state (DEFAULT) then in step  1180  a determination is made as to whether the fresh food compartment is cooling. If it is not, then in step  1178  a request is made for the damper to be closed. If it is, then in step  1182  a request is made for the damper to be open. Returning to step  1170 , if the refrigerator is in a DEFAULT state, then in step  1184  a request is made to close the damper. 
       FIG. 52  illustrates one embodiment of a flow diagram for the control defrost heater subroutine  592 . In step  1200  the refrigerator state is selected. If the refrigerator state is DEFROST or DRIP, then in step  1202  the defrost heater is turned on. If the refrigerator state is a different or DEFAULT state then in step  1204  the defrost heater is turned off. 
       FIG. 53  illustrates one embodiment of a flow diagram for the control evaporator fan subroutine  588 . In step  1210 , the refrigerator state (FridgeState) is selected. If the state is COOL or SUBCOOL then in step  1212  a determination is made as to whether the ice maker is in the melting state (MELTING). If it is, then in step  1214 , the evaporator fan is turned full-on at the rail voltage. If not, then in step  1216 , a determination is made as to whether the freezer is in a cooling (FZCooling) state. If it is, then in step  1218 , the evaporator fan is turned on at less than the rail voltage. If not, then in step  1220 , a determination is made as to whether the ice compartment is cooling (ICCooling). 
     The evaporator fan motor speed is adjusted based upon the state of the ice making compartment, the freezer compartment and the fresh food compartment as shown in  FIG. 53 . The first step is to check the refrigerator state, if the state is cool or subcool then if the ice making compartment is above a predetermined temperature (defined as MELTING in step  1212 ) the fan motor is energized at the highest voltage to produce the maximum air flow. If the ice making compartment is not above the MELTING temperature, then the state of the freezer compartment is evaluated. If the freezer compartment requires cooling, the fan is energized at a high speed to provide the air flow required to adequately cool the freezer compartment, if the freezer does not require cooling, then the fresh food compartment and the ice making compartment are evaluated; if the fresh food requires cooling or if the ice making compartment requires cooling then the fan is energized at a lower voltage to maintain a continuous flow of air through the evaporator compartment without over cooling the freezer compartment. If the air damper is opening or closing then the fan is energized at the lower voltage. If none of these conditions are true, the fan is turned off. 
       FIG. 54  illustrates one embodiment of a flow diagram for the control ice box fan subroutine  590 . In step  1230 , a refrigerator state (FridgeState) is determined. If the refrigerator state is COOL or SUBCOOL, then in step  1232 , the ice maker state is selected. If the ice maker state is MELTING, then the ice box fan is turned full-on in step  1240  such as by applying the rail voltages to the ice box fan. If the ice maker state indicates that the heater is on (HTR_ON), then the ice box fan is turned of in step  1242 . If the ice maker state is in a different or DEFAULT state, then in step  1234  a determination is made as to whether the fresh food compartment is in a cooling (FFCooling) state. If it is, then in step  1244  the ice box fan is turned at less than full voltage to conserve energy. If not, then in step  1236  a determination is made as to whether the ice compartment is in a cooling (IceCooling) state. If it is in then in step  1246 , the icebox fan is turned on at a higher voltage than in step  1244 . In step  1238 , if neither the fresh good compartment is cooling or the ice maker compartment is cooling, the ice box fan is turned off. Thus the ice box fan is controlled in an energy efficient manner. 
     Another aspect of the control system relates to damper operation. Referring to  FIG. 40A , the damper  518  is a switched input. As shown in  FIG. 55 , one methodology provides for monitoring the switched input and timing the lengths and sequences of the switch state in step  1502 . In step  1504  a determination is made as to whether the sequence of switch openings and closings is out of tolerance. If they are, then step  1506  provides for waiting for proper timing sequences to determine damper state. In step  1508 , a determination is made as to whether or not the damper is operating properly. If the damper is not operating properly because it is frozen in place, then in step  1510  the motor output associated with the damper is pulsed. This action uses the motor as a heater to free the damper. 
     The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention.