Pickup 2WD L4-2350cc 2.4L SOHC (1990)
Coolant Temperature Sensor / Switch HVAC: Description and Operation
Coolant Temperature Switch Location
The coolant temperature switch, mounted in the thermostat housing, allows the "A/C ON" signal to be transmitted to the ECU.
When the engine coolant temperature is below 239° F, the bimetal strip inside the switch completes the circuit. This allows the ECU to determine if
conditions are suitable for A/C operation. When the coolant temperature exceeds 235° F, the bimetal strip inside the switch opens circuit. This
prevents the signal from being sent to the ECU.