Checking the thermal switch (diesel) (Mondeo 1)

The thermal switch in a diesel engine is located at the bottom of the radiator. It turns on the electric fan when the coolant temperature reaches a certain value. It is necessary to check the thermal switch if the electric fan does not turn on when the engine is hot. Prerequisites for checking: the thermostat must be OK. If the thermostat does not open, the thermal switch cannot turn on the fan because it is not heated by the coolant.

Caution! In 4-cylinder petrol engines, the cooling fan is switched on/off depending on the engine temperature by the engine control unit.

Disconnect the plug from the thermal switch.

Connect both terminals of the plug with a short control wire.

Turn on the ignition. If the fan now turns on, the thermal switch needs to be replaced.

Check the tightness of the seat and the quality of the contact of the plug on the fan motor. Check the electrical wires and the fan relay, see item 20.4.

Screw in a new thermal switch with a new sealing ring and check its functions. Warm up the engine; the engine should idle until the fan comes on to cool the coolant.