Evaporator Temperature Sensor / Switch: Description and Operation

The A/C thermostat is located on the evaporator housing. The A/C thermostat turns OFF the A/C compressor clutch if the temperature at the evaporator goes below 3°C (37°F). This prevents condensation from freezing on the evaporator fins and blocking the air delivery into the passenger compartment. If the temperature goes below 3°C (37°F), the A/C thermostat goes OFF, removing ground from the condenser fan relay. This deenergizes the relay, removing voltage from the condenser fan motor, and the fan stops running.