The thermal switch turns on the fan at a certain coolant temperature. The switch should be checked if the fan does not turn on when the radiator is hot. Before checking the thermal switch, make sure that its electrical wiring is in good condition (see chapter Onboard electrical equipment), as well as the thermostat and safety valve in the radiator cap. In case of any damage to these parts, the thermal switch cannot work, because. however, it is not heated by the coolant.
The radiator fan can automatically turn on when the engine is off and the ignition is on (position «II» ignition key). Due to the processes of heat removal taking place in the engine compartment, this can happen repeatedly. Therefore, if possible, when working in the engine compartment, turn off the ignition.
1. Drain the coolant.
2. Disconnect the thermal switch connector. On gasoline engines, the thermal switch is screwed into the radiator at the bottom near the right expansion tank of the cooling system, and on a diesel engine, at the bottom near the left expansion tank.
3. Unscrew the thermal switch.
4. Hang the thermal switch in the water bath and heat the water slowly.
Checking the ECT sensor
5. Check the thermal switch circuit with an ohmmeter. With the thermal switch removed, no current should flow (resistance is infinite). When the switch is in the closed state, the current must flow (resistance = 0 ohm). When the thermal switch is turned on, a click should be clearly audible.
6. The thermal switch should switch on at a temperature of approx 100 deg.
7. Let the liquid in the water bath cool down and check if the thermal cut-out operates at the temperature 95 deg.
8. If the thermal switch does not meet the above parameters, it should be replaced.
9. Screw in the thermal switch with a new sealing ring 20 Nm.
10. Connect electrical wiring.
11. At the end of the installation, charge and bleed the cooling system.
12. Warm up the engine and let it idle until the radiator fan turns on. Check the coolant level again.
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