Compressor HVAC: Description and Operation

- The refrigerant temperature switch, which senses the temperature of the refrigerant, is deactivated with temperature 155°C (311°F) or higher.
- When the air conditioning switch is set to the "DRY" mode, the air thermo sensor detects the temperature of the air emitted from the evaporator; the A/C compressor clutch relay is switched OFF if the temperature is 2.2°C (360°F) or lower. Furthermore, when the air conditioning switch is set to the "ECONO" mode, the A/C compressor clutch relay is switched off at temperatures of 7°C (450°F) or below.
- The dual pressure switch turns OFF when the refrigerant pressure becomes excessively high or low, thus protecting the compressor circuit.
- The air conditioning compressor clutch rela is energized when the refrigerant-temperature switch, the air thermo sensor are ON and the dual-pressure switch is ON and the ignition switch, blower switch and air conditioning switch are all ON.
- However, note that the air conditioning compressor clutch relay is switched OFF when starting and during low rpm operation until a certain fixed time has passed, depending upon the running conditions, in order to prevent engine stall and engine vibrations.