Checking the additional fan activation (VW Passat B3)

In all petrol engines except those designated 1F and RP (engines with Mono-Jetronic system), an additional fan activation is provided to avoid excessive temperature increase in the engine compartment and, accordingly, to cool the valve injectors, due to which the starting qualities of a hot engine are improved. If, after switching off a hot engine, the temperature in the intake manifold area rises above +110°C, the temperature sensor connects the time relay to ground and thereby switches on the first stage of the radiator fan. After the temperature drops below +103°C, the temperature sensor breaks the connection of the relay with ground, and the fan switches off. Due to the release of heat in the engine compartment, this process can be repeated many times. The temperature sensor is located next to the intake manifold, the time relay is designated 220 and is located above the relay board of the central distribution device.

Examination

Turn the ignition on and off.

Note: Since the time relay is in working condition for only 10 minutes after turning the ignition on/off, the check should be performed during this time interval.

Disconnect the wire from the temperature sensor and connect it to ground. The fan should start working at the first stage.

Otherwise, check the wires according to the electrical diagram, replace the time relay if necessary.

(The original information is posted on the resource: «www.VWmanual.ru»)