Abstract: An energy saving HVAC system for a passenger compartment of an over the road vehicle comprises a controllable air conditioner system for directing cooled air flow through the passenger compartment. A controllable heater system directs heated air flow through the passenger compartment. A user control panel includes user input devices for manually selecting operating parameters of the HVAC system, one of the user input devices comprising an economy mode selector. A controller is operatively connected to the air conditioner system, the heater system and the user control panel. The controller normally controls the air conditioner system or the heater system in accordance with manually selected operating parameters and, responsive to a user manually selecting the economy mode, overrides the manually selected operating parameters and controls the air conditioner system or the heater system at a preselect energy saving level responsive to the economy mode being selected.