Abstract: An auxiliary power unit for providing power and HVAC to a vehicle. The auxiliary power unit is mounted to the vehicle in a variety of ways, but such that it can be readily moved away from the vehicle for service and maintenance. The power unit has a removable condenser and fan assembly that can be mounted to the power unit or remote from the human occupied portion of the vehicle. The power unit also including a programmable engine control unit for controlling and monitoring various aspects of the operation of the power unit and the vehicle. The power unit having a user interface that enables in-vehicle control of the engine control unit and remote control the engine control unit. The engine control unit monitoring when excessive power requirements of the power unit exists and limiting the air conditioning services of the power unit until the excessive power requirements no longer exists.