The present invention concerns a method for cooling a passenger compartment in a hybrid vehicle that operates an engine intermittently during vehicle operation. The hybrid vehicle includes an HVAC system having an HVAC duct, a blower for directing a flow of air through the HVAC duct, an evaporator located within the HVAC duct, and a heater core. The heater core has a coolant inlet outlet and is located downstream of the evaporator in the HVAC duct. The method includes the steps of cooling a refrigerant; inducing a flow of the cooled refrigerant through the evaporator; blocking a flow of coolant through the coolant inlet and outlet to trap coolant in the heater core; activating the blower to move air through the evaporator and heater core; turning off the vehicle engine; measuring a duct outlet temperature; and starting the engine when the measured duct outlet temperature is above a predetermined temperature.