Heating and Air Conditioning: Description and Operation

CONDENSER FAN AND RADIATOR FAN CONTROL
- For the operation of each fan, see COOLING SYSTEM. Description and Operation

A/C Compressor Relay ON Conditions:

COMPRESSOR CONTROL
- The Fin Thermo sensor which senses the temperature of the air sent to the evaporator, and the air thermo sensor, which senses the temperature of the air flowing out of the evaporator, are 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 off at 115°C (239°F) or higher temperatures.
- The triple pressure switch (or dual pressure switch) turns OFF when the refrigerant pressure becomes excessively high or low, thus protecting the compressor circuit.
- When these three sensors are all activated, the triple pressure switch (or dual pressure switch) is ON, and the ignition switch, blower switch, and air conditioning switch are ON, the A/C compressor relay is energized.