Patent ID: 8327658

Claim:
A method of controlling a heating, ventilation, and air conditioning (HVAC) system, comprising: determining when an ambient zone temperature is equal to or less than a first temperature limit; calculating a first length of time using a first timer, the first length of time being the length of time that a first compressor operates at a first capacity to deliver refrigerant to a first circuit of a first heat exchanger and during which operation the ambient zone temperature is equal to or less than the first temperature limit; reversing a direction of refrigerant flow of the HVAC system when the first length of time is equal to or greater than a first time limit; determining when the ambient zone temperature is equal to or less than a second temperature limit, the second temperature limit having a value higher than the value of the first temperature limit; calculating a second length of time using a second timer, the second length of time being the length of time that the first compressor operates at a second capacity to deliver refrigerant to the first circuit of the first heat exchanger, the second capacity being different than the first capacity, and during which operation the ambient zone temperature is equal to or less than the second temperature limit; and reversing the direction of refrigerant flow of the HVAC system when the second length of time is equal to or greater than a second time limit.