A heating, ventilating and air conditioning (HVAC) system for use in an over-the-road or off road vehicle is provided. The HVAC system may be operated regardless of the operational state of the engine. That is, the HVAC system may be operated to condition the interior compartments of an over-the-road vehicle while the engine is running and while the engine is in a no-idle (off) condition. In general, the HVAC system efficiently shares one or more typical air conditionings components with those already found in the vehicle. In one instance, the HVAC system operates an electrically-driven compressor when a belt-driven compressor is idle. In another case, the HVAC system operates both an electrically-driven compressor and a no-idle condenser when a belt-driven compressor and condenser are idle. In yet another embodiment, the HVAC system shares an evaporator.