Automotive HVAC system and method of operating same utilizing trapped coolant

A method for cooling a passenger compartment in a vehicle that operates an HVAC compressor intermittently during vehicle operation, the vehicle having an HVAC system including an HVAC duct, a blower adapted to direct a flow of air through the HVAC duct, an evaporator located within the HVAC duct, and a heater core, which has a coolant inlet and a coolant outlet and is located downstream of the evaporator in the HVAC duct, the method comprising the steps of:

• a) cooling a refrigerant;
• b) inducing a flow of said cooled refrigerant through said evaporator;
• c) blocking a flow of coolant through at least one of said coolant inlet and said coolant outlet to thereby trap a predetermined amount of coolant in said heater core;
• d) activating said blower to move air through said evaporator and heater core and actuating a damper in said HVAC duct to direct the air through said heater core;
• e) cycling said compressor off;
• f) measuring a duct outlet temperature;
• g) cycling said compressor an when the measured duct outlet temperature is above a predetermined;
• and
• h) prior to actuating said damper, actuating another damper in said HVAC duct to provide only recirculated air to said HVAC duct.

A method for cooling a passenger compartment in a vehicle that operates an HVAC compressor intermittently during vehicle operation, the vehicle having an HVAC system including an HVAC duct, a blower adapted to direct a flow of air through the HVAC duct, an evaporator located within the HVAC duct, and a heater core, which has a coolant inlet and a coolant outlet and is located downstream of the evaporator in the HVAC duct, the method comprising the steps of:

• cooling a refrigerant;
• inducing a flow of said cooled refrigerant through said evaporator;
• blocking a flow of coolant through at least one of said coolant inlet and said coolant outlet to thereby trap a predetermined amount of coolant in said heater core;
• activating said blower to move air through said evaporator and heater core;
• cycling said compressor off;
• measuring a duct outlet temperature;
• cycling said compressor on when the measured duct outlet temperature is above a predetermined temperature;
• measuring an evaporator air outlet temperature;
• measuring a heater core surface temperature;
• blocking the flow of air through the heater core when the evaporator air outlet temperature is less than the heater core surface temperature and the compressor is off;
• and
• continuing the flow of air through the heater core when the evaporator air outlet temperature is not less than the heater core surface temperature and the compressor is off.