Operation CHARM: Car repair manuals for everyone.

Compressor HVAC: Description and Operation

- When the air conditioning switch is pushed in (A/C switch: ON) or the air outlet change over control knob is moved to the DEF or DEF/FOOT position (defroster switch: ON), the air conditioning system operates and compressor control starts.
- The fin thermo sensor, which senses the temperature of the air flowing out of the evaporator, is deactivated with temperature 3.2° C (38° F) or below.
- Here, the engine coolant temperature sensor senses the temperature of engine coolant, and it is turned oft at 115° C (239° F) or higher temperatures.
- The dual pressure switch turns OFF when the refrigerant pressure becomes excessively high or low, thus protecting below.)
- When these two sensors are all activated, the dual pressure switch is ON, and the ignition switch, blower switch, and air conditioning switch (or defroster switch) are ON, the A/C compressor relay is energized.