Cooling Fan Thermal Switch — Checking, Removing and Installing (Audi 80 B3)

1. If the thermal switch at the base of the radiator is damaged, most likely due to a break in the circuit. Because of this, the fan motor will not turn on even when the coolant reaches operating temperature.

2. To check the thermal switch for an open circuit, disconnect the wiring, connect a piece of wire between the ground and the power wire. The fan should start working (even with the ignition off), this means that the thermal switch is faulty and must be replaced.

3. Before removing the thermal switch, drain the cooling system as described in Chapter 3.

4. Disconnect the negative battery cable.

5. Disconnect the electrical wiring, then unscrew the thermal switch from the radiator, remove the sealing gasket.

6. To check the operating temperature of the thermal switch, place it in a pan of water so that only the screw end of the switch is immersed and the electrical contacts are above the water. Attach an ohmmeter between the terminals of the switch. Place the thermometer in the pan, heat the water and note the temperature at which the switch closes, the ohmmeter should read zero. Allow the water to cool and note the temperature at which the switch opens. Replace the switch if the operating temperatures are not within the specified range.

7. Installation is carried out in the reverse order. Always install a new sealing gasket. Fill the cooling system as described in Chapter 5.

(This article was previously published on the resource: «AudiManual.ru»)