An extended engine off passenger climate control system utilizes an advanced
temperature
control module in combination with modifications to the conventional heating/ventilation/air
conditioning (HVAC) system to provide occupants in the passenger cabin of a hybrid
electric motor vehicle with adequate heat or air conditioning for up to two minutes
after the gasoline engine is turned off. A two stage orifice between the condenser
and the evaporator of the air conditioning system slows the equilibration of the
pressures on the high pressure side and low pressure side of the air conditioning
system when the air conditioner compressor is turned off, allowing the passenger
cabin to continue receiving cooling air even when the gasoline engine, and thus
the compressor, is off. An auxiliary engine coolant pump circulates heated engine
coolant through the heater core when the gasoline engine is turned off, thus providing
heat when conditions require passenger cabin heating.