Abstract: An HVAC system for heating and cooling a passenger compartment of a vehicle is provided. A first heat exchanger transfers heat between a primary loop and a secondary loop. The primary loop is a reversible loop and uses high pressure refrigerant. A compressor pressurizes the refrigerant. A second heat exchanger selectively transfers heat energy to and from the passenger compartment. The secondary loop is a low pressure liquid coolant loop that passes through the first heat exchanger. A pump moves fluid through the secondary loop. A third heat exchanger transfers heat to and from an external medium from the fluid passing through the secondary loop. A secondary heat source adds heat to the secondary loop during a heating mode. A bypass means selectively bypasses the secondary heat source during a cooling mode.

Abstract: An air conditioning system for cooling an environment in an over-the-road vehicle is provided. The air conditioning system includes an electrically driven, variable speed compressor, which enables operation of the system when the engine of the over-the-road vehicle is not running. The system is modular and is adapted to be installed in the side luggage compartment of the vehicle to enable existing vehicles to be retrofitted to provide no-idle air conditioning. The housing of the system defines two flow paths therethrough; one cold air path and one hot air path. The hot air path is configured to intersect the condenser at least two times, and draws and expels the air through the same wall of the housing. An air direction device is used to reduce the amount of air recirculation through the hot air path to increase the efficiency of the system.