Abstract: The present invention is directed to an auxiliary power unit for use with a vehicle, typically a truck. The truck has a cab and a sleeper to which the auxiliary power unit provides auxiliary air conditioning and heating. The truck also has a cab evaporator, a sleeper evaporator, a compressor, a condenser, and a plurality of refrigerant lines, a cab heater, a sleeper heater, and a plurality of coolant lines. The auxiliary power unit has an auxiliary evaporator and a plurality of auxiliary refrigerant lines. The auxiliary evaporator is arranged in series with the sleeper evaporator and the sleeper heater. The auxiliary refrigerant lines are separate and distinct from the truck's plurality of refrigerant lines. The auxiliary power unit also has a plurality of auxiliary coolant lines which are interconnected with the truck's plurality of coolant lines.

Abstract: A housing (28) has parallel passageways (30). Each passageway (30) has an inlet port (34) and an outlet port (32). A valve stem (26) with a head (36) reciprocates in each passageway (30) to control the outlet port (32). A flat plate (22) rotates perpendicularly to the stems (26) and has flat surface portions (48) and cavities (46). The positioning of portions (48) and cavities (46) is programmed to bring one of them into alignment with each stem (26) when plate (22) is in any one of a number of predetermined positions. When a portion (48) is moved into alignment, it bears against the head (36) and moves the stem (26) inwardly against a spring (38) into a second position. When a cavity (46) is moved into alignment, the stem (26) is urged into its first position by spring (38) and its head (36) extends into the cavity ( 46).

Abstract: A desired temperature within the passenger compartment (10) of a motor vehicle is selected by occupant movement of a control lever (80) for a variable resistor (VR2). The temperature of conditioning air being supplied to the compartment is measured by a thermister (72). The two temperatures are electronically compared. If the measured temperature is higher than the selected temperature, a solenoid (62) is energized which moves a control valve (48) in a position allowing passage of pressurized air into an air cylinder (26). The air cylinder (26) functions to close a valve (22) in a water line (18, 20) which extends from the engine cooling system to a heat exchanger (24) located within the conditioning air duct (12). When the temperature of the conditioning air falls below the selected temperature level, the solenoid (62) is de-energized and a spring (54) moves the control valve (58) into a position in which it blocks flow of compressed air to the air cylinder (26) and vents the air cylinder to the atmosphere.