Evaporator Temperature Sensor / Switch: Description and Operation

A/C Thermostat

Purpose and Operation
The thermostat measures the temperature of the evaporator via a capillary tube. It controls the power supply to the pull-in coil (terminal 86) of the compressor clutch relay.


When evaporator temperature falls below 32°F (0°C), the thermostat switch will open. The compressor clutch relay will then open and switch the compressor off to prevent evaporator "ice-up"