Patent ID: 8740103

Claim:
A method of heating air flowing through a heater core of a HVAC module, the method comprising the steps of: (a) flowing air through an evaporator of the HVAC module; (b) flowing essentially all of the air flowing through the evaporator through a heater core for all HVAC operating conditions; (c) opening a flow control valve to cause a flow of heated coolant flowing from and heated by an engine into the heater core long enough to replace coolant in the heater core with the heated coolant from the engine; (d) after step (c), closing the flow control valve to stop the flow of the heated coolant into the heater core when the heated coolant has replaced the coolant in the heater core, whereby the air flowing through the heater core absorbs heat from the heated coolant; (e) determining a temperature of the heated coolant as the air flows through the heater core absorbing heat from the heated coolant; and (f) repeating steps (c) through (e) when the temperature of the heated coolant determined in step (e) is determined to have cooled to a predetermined temperature threshold.