Auxiliary Power Units

At Great Plains Transport, we utilize two different APUs


With any APU, there are a few tips and tricks to keep in mind when operating the unit.

1. These units are designed to maintain temperature.

2. If the outside temperature is outside of 10-90 degrees fahrenheit, you are expected to idle your truck and not depend solely on the APU.

3. These units are plumbed directly to the heating/cooling system of your truck. They will kick out the same temp as what your cabin is already set to. Therefore, it’s imperative to keep in mind that these units are only expected to keep the current temperature of your cabin as it is when you turn on the unit.

4. There is a 8-10 hour timer on these units. Make sure to reset the unit before you go to bed!

5. The Thermo King draws fuel from the truck’s diesel fuel tank and is powered by the truck’s batteries. When Fan Only or Heat mode are selected Fan Speed will default to OFF.


  • If want to maintain your cabin temperature, make sure to start the unit immediately upon arriving at your destination.
  • Shut your curtains, all of them. This will help insulate the cabin temperature and help to maintain a comfortable atmosphere.
  • Check the oil often.


  • Expect the unit to heat or cool your cabin temperature immediately. APUs are only expected to maintain temperature.
  • Shut down your engine for hours and expect the APU to heat or cool your cabin significantly in a short period of time.

Thermo King TriPac® Evolution Diesel APU

Thermo King’s next-generation APU provides virtually unlimited sleeper cab heating and air conditioning while reducing tractor idling and lowering maintenance costs. In addition to delivering significant fuel savings, the TriPac Evolution APU is a valuable driver recruitment and retention tool, offering maximum driver comfort while out on the road. See why the TriPac Evolution is the number one auxiliary power unit in the industry and the number one choice of drivers everywhere!

Carrier ComfortPro® Diesel APU

ComfortPro® diesel auxiliary power units (APUs) from Carrier Transicold are the trucking industry’s all-around performance leaders. No other APU offers the combination of air conditioning, heating, cab power, engine warming, truck battery charging, optional shore power connectivity and a 2,000-hour maintenance service interval found in the ComfortPro diesel units.

Thermo King TriPac® Evolution Diesel APU Operating Instructions
The APU engine will shut down when the sleeper compartment temperature remains near setpoint and the truck batteries are charged. The evaporator fan will continue to run. If sleeper compartment temperature rises above setpoint by more than the Dead Band setting (default 3 F) the APU engine will restart and compressor clutch will re-engage. Battery voltage sensing and engine coolant temperature sensing are enabled for the APU. Refer to Monitor Mode.
Fan Mode
The TriPac evaporator fan can be turned on with the Fan Speed Selector knob to provide additional air circulation in the sleeper compartment and truck cab. Three fan speeds can be selected (Low, Medium, High). LEDs around the Fan Speed Selector will indicate the selected speed. Battery voltage sensing and engine coolant temperature sensing are enabled for the APU. Refer to Monitor Mode.
Heat Mode
The air heater is a separate module that heats the sleeper compartment to the setpoint selected with the Temperature Selector knob. Sleeper compartment temperature is sensed inside the air heater, it does not use the Cab Temperature Sensor on the HMI. All heater function is controlled by a separate module inside the heater. The TriPac evaporator fan is defaulted to OFF when Heat Mode is selected. It can be turned on to provide additional air circulation. Battery voltage sensing and engine coolant temperature sensing are enabled for the APU. Refer to Monitor Mode.
Carrier ComfortPro® Diesel APU Operating Instructions

Programmable User Control Panel
Lockable digital control for air conditioning, heating and fan.


APU Power Plant

  • Tier 4 final 2 cylinder diesel engine
  • Alternator 60 Amps @ 12-15 volts DC
  • Generator, 6kW rating @ 110/120V, 60Hz AC – 5.2kW available power
  • Weight: 375 lbs.

Under Bunk Climate Control Unit

  • Airflow, 650 cfm
  • Air Conditioning 12,000 BTU/hr
  • Hermetic compressor
  • Refrigerant R-134a
  • Heating – Up to 10,000 BTU/hr
  • Weight: 85 lbs.
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