Checking the thermal switch

The thermal switch is attached to the bottom of the radiator next to the drain fitting. When a certain temperature of the coolant is reached, it turns on the electric fan. The switch should be checked if the electric fan does not turn on when the radiator is hot. Test Conditions: Thermostat and radiator cap bleed valve are working properly. If these parts are defective, the thermal switch does not turn on the fan, since it is not heated by the coolant.

• Remove the thermal switch connector.

Bridge both pins of the connector with a wire. If the fan turns on, replace the thermal switch.

• If not, check the contacts and connection of the fan motor connector Check wiring, relay and fan motor according to the wiring diagram.

• Screw on the new thermal switch with a tightening torque of 30 Nm. First apply a thread sealant, such as MITSUBISHI 3M-ATD-8660.

• Top up coolant.

• Warm up the engine and let it idle until the fan comes on. Check the coolant level again.

• You can also check the thermal switch when it is removed. To do this, connect an ohmmeter to its contacts.



• Dip the thermoswitch in hot water up to the thread and measure the resistance. At 85°± 3°C, the resistance should be 0; at temperatures below 78°C, it should be ∞.