Thermo King's TriPac auxiliary power unit (APU) provides cab cooling or heating along with engine block heating, battery charging and 12-volt power (an optional inverter provides 120-volt power). However, unlike many other APUs, it provides the cab heat from a fuel-fired heater. The APU engine shuts down for cab heating and lets the bunk heater run on diesel fuel.
TriPac is powered by a Yanmar diesel engine, the same engine that is installed in many Thermo King truck refrigeration units. The engine and belt-driven air-conditioning compressor are mounted on the frame rail of the truck. The evaporator box is typically installed under the sleeper bunk, and the condenser is mounted outside on the back wall of the sleeper cab. These components are controlled by a microprocessor mounted under the sleeper bunk and a control panel mounted in the sleeper cab.
TriPac incorporates start/stop technology that shuts down the system when the parameters have been met in order to further reduce fuel consumption and engine wear. Invented by a refrigeration unit dealer, the TriPac is serviced by Thermo King dealers nationwide.