Abstract:
A system and method for identifying refrigerant-based air conditioning system component-mode failures to provide field technician assistance in diagnosis and repair. A multiplicity of measurement probes for system pressure, system temperature, ambient temperature, ambient relative humidity and refrigerant identification are utilized with a microprocessor unit and a Weighted Probability Inference Engine (WPIE) process. Measured parameters are stored during specific modes of air conditioning system operation and are compared to a stored database of failure modes to determine potential system component-mode failures and provide troubleshooting guidelines. Specific failure modes are displayed to the user through a variety of interface devices.

Description:
[0001]    This application is a continuation-in-part of U.S. Provisional Patent Application No. 60/236,831, filed Sep. 29, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates generally to troubleshooting and repair guidelines for refrigerant-based air conditioning systems. More specifically, the present invention relates to a system and method to provide component-mode failure analysis of an air conditioning system based on a combination of software analysis and physical data measurements under specific air conditioning system operational conditions.  
         BACKGROUND OF THE INVENTION  
         [0003]    Refrigerant-based air conditioning systems are comprised of numerous components that can include, but are not limited to, compressor, condenser, evaporator, metering device such as a TXV valve or orifice tube, filter/dryer, accumulator and refrigerant charge. The object of any air conditioning system is to remove heat and humidity from a specified room or living space and expel the removed heat and humidity to the outside environment. The principles and laws governing the physics and mechanics of an air conditioning system are well known by those skilled in the art.  
           [0004]    Most air conditioning systems are not manufactured or supplied with onboard system diagnostic indicators or features. When an air conditioning system fails to perform adequately the troubleshooting, diagnosis and repair of the air conditioning system is left to the field technician. System parameters such as pressure, temperature and electrical properties are measured by the field technician and compared to data charts supplied by the air conditioning system manufacturer. Often the manufacturer supplied data charts are not tailored to the specific air conditioner application parameters, or may be incomplete or incorrect. The field technician can also unknowingly introduce errors into the diagnosis through a misunderstanding of the measured data, a misunderstanding of the supplied manufacturer data or through inaccuracies inherit in old or outdated equipment.  
           [0005]    Errors in air conditioning system diagnosis can lead to unnecessary costs to the customer, the technician or the original equipment manufacturer. A diagnosis error can easily lead to the replacement of a system component that is not at fault, or the cause of the system, wasting technician time and materials, thereby potentially transferring costs to the customer potentially causing erroneous warranty costs to the original equipment manufacturer.  
           [0006]    In general, the majority of the air conditioning markets do not have standardized tools or procedures to facilitate efficient and effective air conditioning component-mode failure analysis. Technicians are left to rely upon the old technology of pressure gauge sets, temperature probes, voltage and current meters, intuition and past experience to determine component-mode failures. Furthermore, it is not unusual for published air conditioning troubleshooting and diagnostic guides to be incorrect or out of date. This is particularly true with the advent of alternate refrigerants replacing the more common refrigerant types in accordance with the Montreal Protocol.  
           [0007]    Bright Solutions of Troy Mich. currently markets a microprocessor-based, refrigerant-based air conditioning system troubleshooting and component-mode diagnostic tool known as the A/C Investigator, part number E95000. This device has deficiencies, however, in that the A/C Investigator requires multiple probes and requires the technician to make manual corrections of data that do not fall within the recommended ambient operating conditions. Additionally, the A/C Investigator requires the air conditioning system to be operated with a specific RPM setting on the system compressor that is difficult to achieve and maintain.  
           [0008]    There is a need for a refrigerant-based air conditioning system diagnostic tool that permits the compressor to be operated at “idle” speeds and requires no interpretation or correction of data by the technician. There is also a need for such a diagnostic tool to provide refrigerant charge purity analysis.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention is a device for testing a refrigerant based system. The device includes input ports for obtaining a operating parameters from the refrigerant based system; a memory for storing a baseline set of system operating parameters; a first processor to process the system&#39;s operating parameters based on the baseline operating parameters and generating a test result; a second processor for providing test results and prompts to the a user based on outputs from the first processor.  
           [0010]    According to another aspect of the invention, the first processor includes a Weighted Probability Inference Engine (WPIE) to construct failure mode fingerprints of the refrigerant based system.  
           [0011]    According to a further aspect of the invention, the failure mode fingerprints are based on historic data stored in the memory and the operating parameters.  
           [0012]    According to still another aspect of the invention, an infrared probe measures temperatures of the refrigerant based system.  
           [0013]    According to yet another aspect of the present invention, operating parameters of the refrigerant based system are obtained; baseline operating parameters are stored in memory; the operating parameters are processed based on the baseline operating parameters and a test result is generated; and the test results are provided to the user and the user is prompted based on the processing results.  
           [0014]    These and other aspects of the invention are set forth below with reference to the drawings and the description of exemplary embodiments of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following Figures:  
         [0016]    [0016]FIG. 1 is a perspective view of an exemplary embodiment of the present invention;  
         [0017]    [0017]FIGS. 2A and 2B are cross-sectional views of an exemplary air conditioning system temperature measurement probe according to an exemplary embodiment of the present invention;  
         [0018]    [0018]FIG. 3 is a side view of the air conditioning system pressure measurement probes utilized in the operation of an exemplary embodiment of present the invention;  
         [0019]    [0019]FIG. 4 is a schematic diagram of the plumbing of an exemplary embodiment of the present invention;  
         [0020]    [0020]FIG. 5 is a schematic block diagram of the electrical/logic connections of an exemplary embodiment of the present invention;  
         [0021]    [0021]FIG. 6 is a flow chart of the Main Operating Process of an exemplary embodiment of the present invention;  
         [0022]    [0022]FIG. 7 is a flow chart of the Self-Diagnostic sub-routine of the exemplary embodiment of FIG. 6;  
         [0023]    [0023]FIG. 8 is a flow chart of the user air conditioning system Data Entry sub-routine of the exemplary embodiment of FIG. 6;  
         [0024]    FIGS.  9 A-C is a flow chart of the Weighted Probability Interference Engine (WPIE) process of an exemplary embodiment of the present invention;  
         [0025]    [0025]FIG. 10 is a flow chart of the Refrigerant Identifier (EID) sub-routine of an exemplary embodiment of the present invention;  
         [0026]    [0026]FIG. 11 is a flow chart of the Pressure Diagnostic (PDR) sub-routine of an exemplary embodiment of the present invention;  
         [0027]    [0027]FIG. 12 is a flow chart of the Vent Temperature Diagnostic sub-routine of an exemplary embodiment of the present invention;  
         [0028]    [0028]FIG. 13 is a flow chart of the Second Level Diagnostic sub-routine of an exemplary embodiment of the present invention; and  
         [0029]    [0029]FIG. 14 is a flow chart of the Third Level Diagnostic sub-routine of an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0030]    There is shown in FIG. 1, an exemplary air conditioning diagnostic system  10  and its various components. The exemplary system  10  is housed in a portable case  12  that provides component protection and storage. Temperature probe  14 , high side pressure probe  16 , and low side pressure probe  18  are supplied within case  12  and connect to ports  20 ,  22  and  24  respectively. Also included is display device  26  which docks in cradle  28  of top panel  30 . In one embodiment of the present invention, display device  26  may be a Personal Digital Assistant (PDA), such as a 3Com Corporation of Santa Clara, Calif. Model Palm III PDA or a Handspring of Mountain View, Calif. Model VISOR PDA. In another embodiment of the present invention, display device  26  may be coupled to system  10  via a wireless connection, such as an RF link or an IR link for example. In yet another embodiment of the present invention, display device  26  may be fixedly mounted to top panel  30  and may be an LCD display or a plasma display, for example.  
         [0031]    Printer and serial data output ports  32  and  34  are supplied hard mounted to top panel  30  and hard wired to internal electronics (not shown). Ambient sensing port  36  is provided on top panel  30  and, in a preferred embodiment of the present invention, consists of a perforated metal screen positioned over ambient temperature and relative humidity sensors (not shown) located under top panel  30 . Power to system  10  may be provided through various means, such as power cord  38  hard mounted to top panel  30  and hard wired to internal electronics to provide standard AC wall electrical power and/or an external or internal DC power source. An infrared emitter  40  is provided and preferably stowed in the lid of housing  12  and will be utilized during air conditioning system component temperature measurements. Optional components air purge vent  42 A, air intake port  42 B, sample filter  42 C and sample exhaust (not shown) are provided when the refrigerant identifier option is supplied. The refrigerant identifier option is manufactured by the Applicant&#39;s Assignee, Neutronics Incorporated, Model ACR-2000 and is described in U.S. Pat. No. 5,610,398.  
         [0032]    There is shown in FIG. 2, an exemplary air conditioning system temperature measurement probe  14  that will be utilized with an infrared emitter  40 , such as thermal target tape, to measure air conditioning system component temperatures and air conditioning system vent temperatures. The temperature probe design is capable of operating as an integral component of the preferred embodiment of the invention or as a stand-alone temperature-measuring device. Handgrip  50  provides a grip for the user and also houses main circuit board  52 , communication line  54  and cowling  56 . Main circuit board  52  preferably contains tactile switch  58  and optional digital display  60 . Tactile switch  58  will be utilized to inform the microprocessor (not shown in this figure) of the preferred embodiment of the invention to read the current temperature at the sensing end of the temperature probe  14 . Digital display  60  will inform user of what temperature measurements are to be taken and at what time; or, in the stand-alone mode, the display  60  provides direct temperature measurement values.  
         [0033]    Communication to the microprocessor is achieved through communication line  54 , which is terminated on one end with a mating connector  62  to probe port  20  (shown in FIG. 1), supported by strain relief  66  and connected to main circuit board  52  through connector  64 . Cowling  56  provides the mounting and passageway for flexible support  68 , communication line  70  and protective covering  74 . In a preferred embodiment, flexible support  68  is an 8 AWG copper wire fitted with end plates to provide secure mounting. Communication line  70  connects to the main circuit board  52  through connector  72  and to sensor circuit board  78  through connector  76  (shown in FIG. 2B). Protective covering  74  is preferably high-strength heat shrink tubing or material of other means that will provide ease of mounting and provide probe protection.  
         [0034]    [0034]FIG. 2B is a detailed view of sensor end  79  of temperature measurement probe  14 . As shown in FIG. 2B, sensor housing  80  houses sensor circuit board  78 , filter  82  (such as an infrared window), foil thermal slide  86  and viewing LED  88 . Sensor circuit board  78  contains infrared temperature sensor  84 , such as that supplied by Melexis of Concord, N.H., under part number MLX90601 and is known to those skilled in the art. When prompted by display  60 , the user will apply infrared emitter  40  (shown in FIG. 1) to the component location indicated (not shown). In one exemplary embodiment, infrared emitter  40  is a thermal target tape, such as a bright colored electrical tape that radiates infrared energy back to the infrared sensor. Normally the air conditioning system component will not always be of proper color to permit the use of infrared technology. When the component temperature is to be measured the foil thermal slide  86  will be positioned away from the infrared window  82 . The face of the infrared window  82  will be positioned onto the measurement location as illuminated by LED  88  and held into position by locating pins  90 . Tactile switch  58  (shown in FIG. 2A) is then depressed to alert the microprocessor to store the temperature reading transmitted from infrared sensor  84 , through sensor circuit board  78 , through connector  76 , through communication line  70 , through connector  72 , into main circuit board  52 , out connector  64 , through communication line  54  and out connector  62 . The aforementioned communication lines, connectors and circuit boards also provide the power required for display  60 , LED  88  and infrared sensor  84  operation.  
         [0035]    When vent temperatures are to be taken the same procedure will be followed with the exception of positioning the foil thermal slide  86  over the infrared window  82 . Infrared thermal technology is not capable of measuring direct air temperature. In order for infrared thermal technology to measure temperature, a thermally conductive and infrared emissive surface is required to emit infrared energy to the infrared detector. The use of foil thermal slide  86 , which consists of a sliding mechanism that positions a thin metallic foil black body in front of the infrared detector  84 , provides a surface indicative of air temperature. The foil must be sufficiently thin to provide adequate temperature change response through contact with the air. For a stand-alone version of the temperature probe  14 , connector  62 , communication line  54  and connector  64  transfer power and a temperature output signal to an external device (not shown).  
         [0036]    There is shown in FIG. 3 an exemplary high side pressure probe  16  and low side pressure probe  18  for use with the preferred embodiment of the invention to transfer refrigerant pressure directly from the air conditioning system into the invention for pressure analysis by a pressure transducer. Low side pressure probe  18  will also be utilized to transfer a vapor refrigerant sample from the air conditioning system into the invention for use by the refrigerant identifier  42 . A compression-type connector consisting of nut  100 A, front ferrule  100 B and rear ferrule  100 C is swaged onto transfer tube  102 . Transfer tube  102  is preferably a small-bore tube of material suitable for the expected pressure ranges that will minimize refrigerant use and loss by its inherently small internal volume.  
         [0037]    Transfer tube  102  is connected to a compression-type male connector fitting  104  known to those skilled in the art. Outer cover  106  provides transfer tube  102  protection from abuse and damage and is preferably constructed of a tough plastic material, such as polyethylene. Male connector  104  is permanently connected to refrigerant coupler  108 ,  110   112  or  114 . Coupler  108  is a high side R12 refrigerant coupler known to those skilled in the art. Coupler  110  is a low side R12 refrigerant coupler known to those skilled in the art. Coupler  112  is a high side R134a refrigerant coupler known to those skilled in the art. Coupler  114  is a low side R134a refrigerant coupler known to those skilled in the art. Other coupler types maybe utilized as dictated by the refrigerant types per air conditioning market sectors. High side coupler  16  and low side coupler  18  will be connected to high side port  22  and low side port  24  (shown in FIG. 1) of the invention. The coupler end of each hose will be connected to the high side and low side service ports of the air conditioning system. Low side probe  18  provides a vapor refrigerant pathway through low side coupler  110  or  114 , through transfer tube  102  and out fitting  100  into the invention for pressure analysis and refrigerant purity analysis. High side probe  16  provides a liquid refrigerant pathway through high side coupler  108  or  112 , through transfer tube  102  and out fitting  100  into the invention for pressure analysis.  
         [0038]    There is shown in FIG. 4 a plumbing schematic diagram of a preferred embodiment of the invention. High side probe  16  and low side probe  18  are connected to the high and low side service ports of the air conditioning system, respectively. High-pressure liquid refrigerant travels through high side probe  16  and through high side port  22  into the invention. Liquid refrigerant travels through plumbing line  200  to pressure transducer  204  and manual bleed valve  202 . Pressure transducer  204  can be any pressure transducer suitable for exposure to liquid refrigerant, such as that supplied by Measurement Specialties of Valley Forge, Pa. under part number MSP-300-500-P-N-1. Liquid refrigerant trapped in high side probe  16  and plumbing line  200  can be manually relieved through valve  202  and plumbing  203  after completion of testing. Low-pressure vapor refrigerant travels through low side probe  18  and through low side port  24  into the invention. Vapor refrigerant travels through plumbing line  206  to pressure transducer  205  and solenoid valve  208 . Pressure transducer  205  is of the same construction as pressure transducer  204  connected to the high-pressure plumbing  200  and provides an electrical signal proportional to the amount of pressure incident upon the transducer. Solenoid valve  208  opens when so commanded by the microprocessor to admit vapor refrigerant gas through plumbing line  210  into refrigerant identifier  42  and out sample exhaust port  214 . Refrigerant identifier  42 , air purge vent  42 A and air intake port  42 C are all components supplied with the refrigerant identifier manufactured by Applicant&#39;s Assignee, Neutronics Incorporated Model ACR-2000 and described in U.S. Pat. No. 5,610,398.  
         [0039]    [0039]FIG. 5 depicts the electrical/logic connections of an exemplary embodiment of the invention. Power cord  38  supplies power from an external source into power supply  250 . Power cord  38  can be of standard AC wall plug construction or can be of DC battery connection design. Power supply  250  regulates and cleans input power and distributes power through conductor  264  to analog amplifier  252 , A/D converter  254 , refrigerant identifier  42  and microprocessor #1  256 . Analog amplifier  252  receives signals from high-pressure transducer  204 , low pressure transducer  205 , system temperature probe  14 , ambient temperature sensor  286  and ambient relative humidity sensor  287  through communication link  268 . Ambient temperature sensor  286  is a solid-state semi conductor device known to those skilled in the art, such as part number LM50 supplied by National Semiconductor Corporation of Santa Clara, Calif. Ambient relative humidity sensor  287  is a variable capacitance device known to those skilled in the art such as part number 232269190001 supplied by Phillips Semiconductors of Eindhoven, The Netherlands.  
         [0040]    Analog amplifier  252  boosts the strength of the input signal and transfers the boosted signal to A/D converter  254  through communication line  265 . A/D converter  254  converts analog signals into digital signals for transfer through communication line  270  to microprocessor #1  256 . Microprocessor #1  256 , such as supplied by Phillips Semiconductors of Eindhoven, The Netherlands under part number 80C552, utilizes input signals from A/D converter  254  and refrigerant identifier  42 , through line  272 , to operate main operating process  300  (shown in FIG. 6) and directs output of information to printer port  32  through line  274 , serial port  34  through line  276 , and display device  26  through hard-wired communication line  278  or radio frequency communication  280 . Display device  26  can be any device deemed suitable to perform the user interface necessary for proper operation of the invention. A PDA, such as a 3Com Corporation of Santa Clara, Calif. Model Palm III Personal Digital Assistant or a Handspring of Mountain View, Calif. Model VISOR Personal Digital Assistant, device is utilized in a preferred embodiment of the invention and contains a second microprocessor  260 . Communication lines  282 ,  284  and  289  relay data and instructions between microprocessor #2  260 , user interface  258 , display module  262  and memory  290  to provide instructions during testing, invention status and test results to the user. Although the exemplary embodiment contemplates two separate microprocessors, those of skill in the art understand that a single microprocessor may be used as desired.  
         [0041]    [0041]FIG. 6 depicts the flow chart of main operating process  300 . Upon power up of the invention, at Step  400 , a self-diagnostic test is performed. Following successful completion of self-diagnostic test  400 , at Step  500 , a system data entry subroutine is entered prompting the user to enter specific information about the specific air conditioning system to be tested. At Step  600 , the WPIE process (described in detail below) builds failure mode “fingerprints” based upon data stored in memory  290  (shown in FIG. 5). The “fingerprints” will be utilized with 2 nd    1000  and 3 rd    1100  Level Diagnostic testing to determine air conditioning system component-mode failures. At Step  302 , the user is instructed to connect high side pressure probe  16  and low side pressure  18  to the low side and high side ports, respectively, of the air conditioning system. At Step  304 , real time system pressures and real time ambient temperature and relative humidity data are presented to the user in real-time on display  262 . At Step  700 , an EID sub-routine makes a determination of refrigerant purity within the air conditioning system. At Step  306 , (A/C system configuration) the user is instructed on how to configure the air conditioning system for testing. Instructions are provided pertaining to cooling control settings, sun load, window positions, blower speeds, or any other specific setting that may be required for testing the specific application. When the user indicates completion of air conditioning configuration completion, pressure diagnosis sub-routine (Step  800 ) determines pressure component-mode air conditioning system failures. Pressure testing will be followed by vent temperature diagnostic sub-routine (Step  900 ) whereby the effective cooling of the air conditioning system is evaluated. If no significant cause for system failure has been established the user is directed to 2 nd  Level Diagnostics sub-routine (Step  1000 ) for additional testing, otherwise the session will end. Under 2 nd  level diagnostics sub-routine  1000  the user is guided through a more in-depth analysis involving the measurement of system pressures and component temperatures to calculate the differential temperature across air conditioning system components. If no significant cause for system failure has yet been established the user is directed at Step  1100  to 3 rd  Level Diagnostics sub-routine, otherwise the session ends. Under 3 rd  level diagnostics sub-routine  1100  the user is guided through additional analysis involving the measurement of system pressures and component temperatures to calculate the differential temperature across air conditioning system components under different operating conditions. When 3 rd  level diagnostics sub-routine  1100  has been completed the user will be informed of the findings of the testing on display  262 . All analysis data will be available to the user for downloading into external computers or printers (not shown). At Step  308 , the user is given an opportunity to retest the existing air conditioning system with a retest prompt. The user can choose to retest, and the process will return back to probe attachment Step  302 , otherwise the session ends.  
         [0042]    [0042]FIG. 7 depicts the Self-Diagnostic Mode sub-routine  400  of the main operating process  300  of a preferred embodiment of the invention. At Step  402  (Verify Internal Communication), all internal communication lines are verified to be operational through means known to those skilled in the art. At Step  404 , a determination is made if the communication test was verified. At Step  424 , failure of the communication test will be reported to the microprocessor and detected error codes will be displayed. If the communication step passes, at Step  406  (Verify Probe Functionality) all probe functions are test to verify proper electrical attachment, electrical function, calibration and status. At Step  408 , a determination is made if the probe test was verified. At Step  424 , failure of the probe test will be reported to the microprocessor and detected error codes will be displayed  424 . If the probe test passes, at Step  410 , an inquiry is sent to the microprocessor to determine if the refrigerant identifier is installed in the invention. The refrigerant identifier will be an expensive feature to the invention and may not be included with every model. If at Step  410 , a refrigerant identifier is identified present, at Step  412  (Load EID Set-Up Information) data such as factory calibration, identifier type, local calibration and local elevation set-up is retrieved from stored memory. If no refrigerant identifier is present the sub-routine will end.  
         [0043]    At Steps  414 ,  416 , refrigerant identifier local elevation settings will be confirmed. If the local elevation requires adjustment, at Step  420 , the user is instructed how to make the adjustment. The elevation is then verified again as aforementioned through steps  414  and  416 . When the local elevation has been properly set, at Step  418 , the refrigerant identifier will be locally calibrated and, at Step  422 , the calibration is confirmed. If the calibration is verified the sub-routine ends and control will return to the main operating process  300 . If the calibration fails, at Step  424 , detected error codes will be displayed on display  262 .  
         [0044]    System Data Entry sub-routine  500  is depicted by FIG. 8. The user will input information specific to the air conditioning system being tested. In a preferred embodiment of the invention, the user will input the Vehicle Identification Number or the test run number (Step  502 ), the refrigerant type (Step  506 ) the refrigerant metering device type (Step  510 ), define the system as a single or dual evaporator type (Step  514 ), indicate the compressor type (Step  518 ), and enter user specific data (Step  522 ) such as, but not limited to, name, address or customer name information. All entered data is stored into the memory (not shown) at Steps  504 ,  508 ,  512 ,  516 ,  520  and  524  for use in display reporting, printouts and downloads. At he completion of Step  522 , the Sub-routine ends and returns to main operating process  300 .  
         [0045]    [0045]FIG. 9A, FIG. 9B and FIG. 9C depict a flow chart of the Weighted Probability Inference Engine (WPIE) process  600 . In a preferred embodiment of present invention, the instrument contains permanent memory storage of failure modes in matrix form and is recalled through the use of variable [Y]. Each failure mode matrix contains a multiplicity of elements denoted by the variable [X]. Each element represents a specific parameter of the air conditioning system. This system of elements is fashioned to create a “fingerprint” of conditions that constitute a specific failure mode as derived through laboratory testing. Maximum and minimum values are also stored in the permanent memory for each failure mode element that define acceptable ranges of each specific air conditioner parameter as determined through laboratory testing. In the preferred embodiment of the invention the failure modes may include, but are not limited to, the following modes as defined by mode number [Y].  
       [Y] Mode Description  
       [0046]    0 Low Performing Compressor  
         [0047]    1 Evaporator Air Flow Restriction  
         [0048]    2 Missing Orifice Tube  
         [0049]    3 Slipping Compressor Clutch or Fan Belt  
         [0050]    4 Cooling Fan Disconnected  
         [0051]    5 Blocked Orifice Tube  
         [0052]    6 No Problem Detected  
         [0053]    7 Condenser Restriction  
         [0054]    8 Blend Door Malfunction  
         [0055]    9 Blocked Condenser Air Flow  
         [0056]    10 Pressure Switch Setpoint Fault  
         [0057]    11 Air in Refrigerant Charge  
         [0058]    12 30% Low Refrigerant Charge  
         [0059]    13 40% Low Refrigerant Charge  
         [0060]    14 Suction Side Restriction  
         [0061]    15 Excessive Refrigerant Charge  
         [0062]    16 TXV Valve Fault  
         [0063]    In turn, in the preferred embodiment of the invention each failure mode may contain, but is not limited to, the following listing of elements denoted by the variable [X].  
       [X] Element Description  
       [0064]    0 Compressor Clutch Cycle Speed  
         [0065]    1 Maximum High Side Pressure  
         [0066]    2 Minimum High Side Pressure  
         [0067]    3 Minimum Low Side Pressure  
         [0068]    4 Maximum Low Side Pressure  
         [0069]    5 Compressor Inlet Temperature  
         [0070]    6 Compressor Outlet Temperature  
         [0071]    7 Compressor Temperature Gradient  
         [0072]    8 Condenser Inlet Temperature  
         [0073]    9 Condenser Outlet Temperature  
         [0074]    10 Condenser Temperature Gradient  
         [0075]    11 Metering Device Inlet Temperature  
         [0076]    12 Metering Device Outlet Temperature  
         [0077]    13 Metering Device Temperature Gradient  
         [0078]    14 Evaporator Inlet Temperature  
         [0079]    15 Evaporator Outlet Temperature  
         [0080]    16 Evaporator Temperature Gradient  
         [0081]    17 Accumulator Inlet Temperature  
         [0082]    18 Accumulator Outlet Temperature  
         [0083]    19 Accumulator Temperature Gradient  
         [0084]    20 Vent Inlet Temperature  
         [0085]    21 Vent Outlet Temperature  
         [0086]    22 Vent Temperature Gradient  
         [0087]    The basic matrix form of [element, mode] or [X, Y] is utilized throughout the WPIE process to construct failure mode fingerprints, construct actual test data fingerprints, compare actual test data fingerprints to failure mode fingerprints, sort comparison results, and finally generate a component-mode failure to user for the specific air conditioning system being tested. In a preferred embodiment of the invention, WPIE process  600  begins at Step  602 , by making a determination as to operate the sub-routine in initialization or test mode. The initialization mode constructs the failure mode fingerprint or Graded Failure Mode (GFM) utilizing the data stored in the permanent memory for the element type and element minimum and maximum values. Initially, at Step  604 , variables [X] and [Y] are set to zero. At step  606 , the value of element [0] stored under failure mode [0] will be retrieved from memory  290 . A determination will be made to rate the retrieved value as exceeding a minimum or maximum by comparing the retrieved element value to the minimum and maximum values stored for the element type. At Step  608 , maximum values are determined utilizing Eq. 1:  
         Mode Element [0,0]&gt;Maximum Limit [0]  Eq. 1  
         [0088]    At Step  610 , the value of failure mode element [0,0] is then graded using Eq. 2 to produce the first element of the Graded Failure Mode or fingerprint.  
         Graded Failure Mode Element [X,Y]=(Element [X]−Max Limit [X])/(Max Limit [X]−Min Limit [X])  Eq. 2  
         [0089]    At Step  612 , this value is stored under Graded Failure Mode Element [0,0]. At Step  618 , minimum values are determined utilizing Eq. 3:  
         Mode Element [0,0]&lt;Minimum Limit [0]  Eq. 3  
         [0090]    At Step  620 , the value of failure mode element [0,0] is then graded using Eq. 4 to produce the first element of the Graded Failure Mode or fingerprint.  
         Graded Failure Mode Element [X,Y]=(Element [X]−Min Limit [X])/(Max Limit [X]−Min Limit [X])  Eq. 4  
         [0091]    At Step  612 , this value is stored under Graded Failure Mode Element [0,0]. At Step  622 , element values that do not exceed either the maximum or minimum limit would be stored to zero. At Step  617 , Variable [X] will increase by one count and, at Step  616 , [X] will be verified that it does not exceed the amount of elements contained in each failure mode fingerprint. In the exemplary embodiment, the maximum value for [X] is 22, but the invention is not so limited in that the maximum number of elements [X] may be defined as necessary to accomplish the desired functions of the invention.  
         [0092]    At Step  606 , the process retrieves the value of element [1] stored under failure mode [0] from the permanent memory. The entire process described above will be repeated until all elements of the Graded Failure Mode [0] have been constructed. In the case of the preferred embodiment of the invention this would require twenty-three iterations to complete Graded Failure Mode [0]. When Graded Failure Mode Element [0,22] has been stored, at Step  616 , variable [X] will exceed the amount of elements available (22) under test. At Step  630 , variable [Y] will then increase by one count. The entire process described above is now repeated for all elements of Failure Mode [1] to produce Graded Failure Mode [1]. Once again, this process is repeated until all Graded Failure Modes have been constructed and stored into the memory. For the preferred embodiment of the invention this would require seventeen iterations to construct all Graded Failure Mode Fingerprints (0 through 16). As previously mentioned above with respect to variable [X], the invention is not limited to 17 iterations of variable [Y], in that additional modes may be defined and included or fewer modes may be utilized based on the specifics of the system under test or other considerations. The Initialization session will now end and control will return to the main program process  300 .  
         [0093]    In the Test Data mode of exemplary WPIE process, test data gathered and stored to memory from the air conditioning system under test during the 2 nd  Level Diagnostic sub-routine (Step  1000 ) and 3 rd  Level Diagnostic sub-routine (Step  1100 ) will be graded and then compared to the data elements of the Graded Failure Modes constructed in the Initialization mode of the WPIE process. This comparison will yield a Failure Result Mode matrix that will be utilized to determine component-mode failure probabilities. At Step  634 , variables [X] and [Y] will be set to zero. At Step  636 , test data from 2 nd    1000  or 3 rd    1100  Level Diagnostic sub-routine testing will retrieved from the memory storage bank Test Data Element [0]. At Step  638 , the difference between the Test Data Element [0] and the Graded Failure Mode Element [0,0] will determined using Eq. 5:  
         Graded Failure Mode Element [0,0]−Test Data Element [0]  Eq. 5  
         [0094]    At Step  640 , the resulting value will be checked to see if it equals zero. At Step  642 , for values that equal zero the Failure Result Mode Element [0,0] will be stored as one (1), which denotes a perfect fit. At Step  644 , For values that do not equal zero the Failure Result Mode Element [0,0] will be stored according to Eq. 6:  
         1−(the difference/Graded Failure Mode Element [0,0]  Eq. 6  
         [0095]    At Step  646 , variable [X] is increased by one count and, at Step  648 , verified that its value does not exceed the number of elements available in the Graded Failure Mode Fingerprint. The above process continues until all elements of Failure Result Mode [0] have been completed. In the preferred embodiment of the invention this would equate to Failure Result Mode [0,22]. At Step  650 , The [Y] variable is increase by one count and, at Step  652 , verified not to exceed the number of Graded Failure modes. The above process continues until all Failure Result Mode Fingerprints have been constructed and stored. In the preferred embodiment of the invention this would require seventeen iterations to complete. At Step  654 , variable [Y] will be reset to zero. At Step  656 , the elements of Failure Result Mode [0] will be totaled and, at Step  658 , stored as Failure Mode Sum [0]. The Failure Mode % Fit will be calculated  660  according to Eq. 7:  
         Failure Mode Fit [Y]=100×(Failure Mode Sum [Y]/Number of Elements)  Eq. 7  
         [0096]    At Step  662 , the results of Eq. 7 is stored as Failure Mode % Fit [0]. At Step  664 , Variable [Y] will increase one count and the process of determining Failure Mode % Fit will be repeated in order to construct all Failure Mode % Fit files. In the preferred embodiment of the invention seventeen iterations would be required. The resulting Failure Mode % Fit files will provide a percent probability for each of the established failure modes to be utilized in the 2 nd  and 3 rd  Level Diagnostic sub-routine of the main operating process  300 . The session will now end and revert to main operating process  300 .  
         [0097]    Refrigerant status is determined with the EID sub-routine  700  depicted in FIG. 10. Sub-routine  700  will first determine, at Step  702 , if the refrigerant identifier feature is present. If no refrigerant identifier is found, at Step  704 , the user will be prompted if the air conditioning system refrigerant has been tested with an external refrigerant identifier. At Step  706 , the user response is input. If no refrigerant testing has been performed, at Step  708 , this information is stored to memory. If the refrigerant has been tested by an external refrigerant identifier, at Step  710 , the user will be prompted to identify if the testing reveled pure refrigerant. Pure refrigerant is defined as 98% by weight of the specified refrigerant type with less than 5% by weight air content. At Step  712 , the user response is entered. If refrigerant is determined to be pure, at Step  714 , the data will be stored to memory. If the refrigerant is determined not to be pure a message of “possible refrigerant contamination” will be given at Step  716 .  
         [0098]    If, at Step  702 , the refrigerant identifier is found to be present, at Steps  718 ,  720 , the local calibration of the refrigerant identifier will be verified. If the calibration has expired it will be repeated at Step  722 , and subsequently verified at Step  718 . If the local calibration is found to be valid the user will be prompted to start the testing at Step  724 . At Step  726 , upon user input to start test, the microprocessor will admit a vapor refrigerant sample from the air conditioning low side service port into the refrigerant identifier for testing at Step  728 . At Step  730 , the results of the refrigerant testing are stored into memory. At Step  732 , a determination will be made of refrigerant purity. Pure refrigerant is defined as 98% by weight of the specified refrigerant type with less than 5% by weight air content. If, at Step  732 , the refrigerant is found to be contaminated, at Step  716 , a message of “possible refrigerant contamination” will be given. If, at Step  732 , the refrigerant is found to be pure the session will end and control will return to the main operating process  300 . With the presence of refrigerant identifier  42 , the user will have the option to purge air detected within the refrigerant charge with the “Air-Purging” feature of the refrigerant identifier.  
         [0099]    [0099]FIG. 11 depicts the Pressure Diagnostics sub-routine  800  of the main operating process  300 . At Step  802 , data from high side pressure transducer and low side pressure transducer will be read by the microprocessor for a 5-minute period. At Step  804 , the maximum and minimum high side and low side pressures will be stored to memory during this period. At Step  806 , a determination will be made if the high side pressure is equal to 0 psi. At Step  808 , a determination will be made if the low side pressure is equal to 0 psi. If the high side or low side pressures are equal to 0 psi, at Step  810 , the user will be prompted to verify that the low side and high side pressure probe coupler valves are open. At Step  812 , the user will input the response. If the probe coupler valves are closed the user will be prompted to open them at Step  814 . Upon user response that the probe coupler valves have been opened, as determined at Step  816 , the sub-routine will restart at Step  802 , by reading the high side and low side pressure transducer readings.  
         [0100]    If the high side and low pressures both equal 0 psi and the probe coupler valves are reported to be open at Step  812 , the user will be prompted, at Step  818 , that the air conditioning system has no refrigerant charge, the session will end and control will return to the main operating process  300 . If the high side pressure is not equal to 0 psi and the low side pressure is not equal to 0 psi, a determination will be made, at Step  820 , if the high side pressure is less than the low side pressure. If it is determined that the high side pressure is less than the low side pressure, the user will be prompted, at Step  822 , to inspect the air conditioning plumbing to verify that the high side and low side connections to the compressor are not reversed, the session will end and control will return to the main operating process  300 .  
         [0101]    If the high side pressure is determined to be higher than the low side pressure then, at Step  824 , the difference in pressure will be calculated as high side pressure less low side pressure. At Step  826 , a determination will be made if the difference in pressure is less than 10 psi. If the difference in pressure is less than 10 psi the user will be prompted, at Step  828 , to inspect the air conditioning system compressor electrical connections, fan belts and other possible compressor faults, the session will end and control will return to the main operating process  300 . If the difference in pressure is greater than 10 psi the high side pressure transducer and the low side pressure transducer data streams will be read, at Step  830 , for a 5-minute period. The data collected and stored at Step  832  from the low and high side pressure transducers will be utilized, at Step  834 , to determine the air conditioning compressor clutch cycling speed. The clutch cycling speed is determined by counting the number of sinusoidal cycles in the pressure readings over a 5 minute period. At Step  836 , a determination will be made as to the status of the clutch cycle speed. Clutch cycle speed will be determined to be normal if there is less than 15 cycles in a 2-minute period, otherwise the speed will be determined to be rapid. The clutch cycle speed status will be stored to memory as normal, at Step  840 , or rapid, at Step  838 , for use with the WPIE process during subsequent testing. The session will end and control will return to the main operating process  300 .  
         [0102]    [0102]FIG. 12 depicts the Vent Temperature Diagnostics sub-routine  900  of the main operating process  300 . At Step  902 , the user will be prompted to measure the vent out temperature using temperature probe  14 . The user will position the vent probe measuring tip  80 , with the foil thermal slide  86  positioned over the sensing window  82 , in the air stream (not shown) exiting the vent of the air conditioning system. When the probe is properly positioned, at Step  904 , the tactile switch  58  of probe  14  is depressed to indicate the measurement is complete. At Step  906 , The temperature data from the probe will be stored into memory. At Step  908 , the user will be prompted to measure the vent in temperature using the temperature probe. The user will position the vent probe measuring tip, with the foil thermal slide positioned over the sensing window, in the air stream entering the intake vent of the air conditioning system. When the probe is properly positioned tactile switch  58  of the probe is depressed to indicate the measurement is complete. At Step  910 , the status of this measurement is determined. Once the measurement is complete, at Step  912 , the temperature data from the probe is stored into memory, otherwise the process returns to Step  908 . At Step  914 , the change in temperature will be determined as the vent out temperature measurement less the vent in temperature measurement. At Step  916 , a determination is made to see if the change in temperature is greater than  10  degrees. If the temperature is greater than 10 degrees, at Step  918 , the data stored from the Pressure Diagnostics sub-routine will be retrieved. At Step  920 , the low side and high side pressure values will be compared to stored acceptable data ranges. If the pressure values are within an acceptable range, at Step  922 , a message “system function passes” will be displayed, the session will end and control will return to the main operating process  300 . If the pressure values are not within an acceptable range, at Step  924 , a message of “run 2 nd  level testing” will be displayed to the user, the session will end and control will return to the main operating process  300 . If, at Step  916 , the change in temperature is determined to be less than 10 degrees, at Step  924 , a message “run 2 nd  level testing” will be displayed to the user, the session will end and control will return to the main operating process  300 .  
         [0103]    [0103]FIG. 13 depicts the 2 nd  Level Diagnostics sub-routine  1000  of the main operating process  300 . At Step  1002 , the user will be prompted to measure the change in temperature across various air conditioning system components. Measurement will be made with the temperature probe foil thermal slide  86  positioned away from sensing window  82  and the sensing window is positioned onto the measuring point. Each measuring point will be covered with thermal target tape  40  to insure that a good temperature reading can be obtained. As each measurement is made tactile switch  58  of temperature probe  14  will be depressed to indicate the measurement is complete. At Step  1006 , the status of this measurement is determined. Each data point that is read from the temperature probe will be stored to memory  1004  for use with the WPIE process. Required temperature measurements can include, but are not limited to, compressor inlet, compressor outlet, condenser inlet, condenser outlet, evaporator inlet, evaporator outlet, TXV or orifice inlet, TXV or orifice outlet. the temperature data from the probe is stored into memory. Once the measurement is complete, at Step  1008 , all temperature measurements taken and previously stored temperature, pressure, clutch cycle speed and refrigerant status data will be utilized to create a test profile of the air conditioning system, otherwise the process returns to Step  1002 . At Step  1010 , the resulting test profile is compared to the WPIE process failure modes to determine possible matches of potential air conditioning system component-mode failures. At Step  1012 , identified potential WPIE failure mode matches are stored into memory with the weighted probability assigned to each mode by the WPIE process. At Step  1014 , the stored WPIE failure modes will be sorted from highest weighted probability to lowest weighted probability. At Step  1016 , a determination will be made if all of the stored weighted modes are less than 90% weighted. If all stored modes are less than 90% weighted then, at Step  1018 , a message of “run 3 rd  level testing” will be displayed, the session will end and control will return to the main operating process  300 . If some of the stored modes are greater than 90% weighted, at Step  1020 , a determination will be made if some of the stored mode are less than 90% weighted. Stored modes with less than 90% weighted probability will be dumped from memory at Step  1022  and the resorting and determinations of  1014 ,  1016  and  1020  will be repeated. When only modes with weighted probabilities greater than 90% remain only the highest component-mode failure(s) will be reported to the user at Step  1024  through the display device. The session will end and control will return to the main operating process  300 .  
         [0104]    [0104]FIG. 14 depicts the 3 rd  Level Diagnostics sub-routine  1100  of the main operating process  300 . At Step  1102 , the user will be prompted to reconfigure the operating parameters of the air conditioning system. Reconfiguration of the air conditioning system can involve, but is not limited to, increasing compressor idle speed or changing air conditioning control settings. At Step  1104 , when the reconfiguration of the air conditioning system is complete the user will inform the microprocessor. At Step  1106 , the user will be prompted to measure the change in temperature across various air conditioning system components. Measurement will be made with the temperature probe foil thermal slide positioned away from the sensing window and the sensing window positioned onto the measuring point. Each measuring point will be covered with thermal target tape to insure that a good temperature reading can be obtained. As each measurement is made tactile switch  58  of temperature probe  14  will be depressed to indicate the measurement is complete (Step  1110 ). At Step  1108 , Each data point read from the temperature probe will be stored into memory for use with the WPIE process. Required temperature measurements can include, but are not limited to, compressor inlet, compressor outlet, condenser inlet, condenser outlet, evaporator inlet, evaporator outlet, TXV or orifice inlet, TXV or orifice outlet.  
         [0105]    At Step  1112 , all temperature measurements taken and previously stored temperature, pressure, clutch cycle speed and refrigerant status data will be utilized to create a test profile of the air conditioning system. At Step  1114 , The resulting test profile will be compared to the WPIE process failure modes to determine possible matches of potential air conditioning system component-mode failures. At Step  1116 , Identified potential WPIE failure mode matches will be stored to memory with the weighted probability assigned to each mode by the WPIE process. At Step  1118 , The stored WPIE failure modes will be sorted from highest weighted probability to lowest weighted probability.  
         [0106]    At Step  1120 , a determination will be made if all of the stored weighted modes are less than 90% weighted. If all stored modes are less than 90% weighted, at Step  1122 , a message “fault not detected” will be displayed, the session will end and control will return to the main operating process  300 . At Step  1124 , if some of the stored mode are greater than 90% weighted a determination will be made if some of the stored mode are less than 90% weighted. At Step  1126 , stored modes with less than 90% weighted probability will be dumped from memory and the resorting and determinations of  1118 ,  1120  and  1124  will be repeated. At Step  1128 , when only modes with weighted probabilities greater than 90% remain, only the highest component-mode failure(s) will be reported to the user through the display device, the session will end and control will return to the main operating process  300 .  
         [0107]    It is contemplated that one exemplary embodiment of the present invention may me a stand alone portable system for testing of both mobile and stationary refrigerant based systems. As used herein, a mobile refrigerant based system may be a system that is part of an automobile, bus, etc. Further, a mobile system may be any system capable of being moved from place to place such as a freezer, refrigerator, window mounted air conditioner, etc. By contrast a stationary refrigerant based system is any system that is not easily moved such as a central home or office air conditioning system.  
         [0108]    Although the invention has been described with reference to exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the true spirit and scope of the present invention.