
| The primary function of the heater and A/C system, also know as HVAC, is to provide air temperature comfort inside your car or truck. All system have mainly the same components: Compressor Evaporator Core Condenser Freon, Hoses and Lines Control Head Heater Core Temperature / Mode doors and a number of other hoses, lines, fittings, valves, motors or actuators and sensors. All of todays newer cars and trucks are electronically controlled by the control head. This is the panel in the dash that you use to change all functions. This panel sends signals to the temperature and mode door motors / actuators to direct air flow and change the temperature of the incoming air. Signals to the Powertrain Control Module (PCM), or Body Control Module (BCM), and then to the compressor to turn it on if all parameters are met. These parameters include many different things such as outside temp, engine temp, throttle position, engine speed, and many others. Any one of these things can prevent A/C compressor engagement. |