Coolant Temperature Sensor / Switch HVAC: Description and Operation

Engine Coolant Ambient Temperature Sensor:

The engine coolant ambient temperature sensor is located on the heater inlet line between the engine and the heater core. It detects coolant temperature and converts it into a resistance value which is then input to the EATC unit. After disconnecting engine coolant ambient temperature sensor harness connector, measure resistance between sensor terminals (1) and (2), using the table below.