Coolant Temperature Sensor / Switch HVAC: Description and Operation
WATER TEMPERATURE SENSORDESCRIPTION
1. Water temperature sensor is located at the heater unit.
2. It detects coolant temperature. Its signal is used for cold engine lockout control. When the driver operates the heater before the engine is warmed up, the signal from sensor causes the heater control unit to reduce blower motor speed until coolant temperature reaches the threshold value.
1. Ignition "ON"
Specification:
2. Using the multi-tester, Measure resistance between terminal "1" and "2" of water temperature sensor.
3. If the measured resistance is not specification, substitute with a known-good water temperature sensor and check for proper operation.
4. If the problem is corrected, replace the water temperature sensor.
NOTE: Negative type thermistor that resistance will rise with lower temperature, and reduce with higher temperature.