Models with 4- and 6-cylinder engines are equipped with an electrically driven fan, which is connected only if the temperature of the coolant rises too high. A 6-cylinder engine usually has two separate fans.
The 5-cylinder engine is different. A so-called viscous coupling fan is installed there. Its connection is not electrical. When the temperature inside the radiator has risen, the force clutch between the pulley, the torque to which is transmitted from the engine through a belt drive, and the fan working disk (impeller) carried out by liquid (Visco-) clutch.
Separate from the main fan, there is a so-called auxiliary blow-down fan after the engine stops: an additional electric fan blows stagnant hot air out of the engine compartment of the 5-cylinder engine after the car has stopped. The same happens in the 85 kW 4-cylinder engine, however, at the expense of the already existing electrically driven fan.
In certain vehicle options (e.g. with factory-fitted trailer hitch or vehicles with enhanced cooling system, as also partly with 6-cylinder engines) next to the already mentioned cooling fan, an additional electric fan is installed.
Models with a 5-cylinder engine do not have room for a second cooling fan. Therefore, when a trailer hitch or air conditioner is installed at the factory to provide additional blow-off fan functions, instead of a conventional 50W fan motor, a larger 300W fan motor is used for additional cooling (via thermal switch).
Functioning of the electric fan of the cooling system. 4 and 6 cylinder engine
You will find the wiring diagrams in chapter «wiring diagrams». Separately, in serial versions, the case is as follows:
A temperature-sensitive switch is screwed into the radiator. If it «feels», that the liquid flowing past it is still hot after passing through the radiator (more than 92°C), it turns on the fan via the relay on the plug box 2 on the relay rack 1 - the central switch (rear left in the engine compartment). It is located in the control circuit of the relay and determines when the contacts that switch the current from terminal 30 should be closed (constantly under tension) to the fan.
The control circuit itself only draws current from the X terminal when the ignition is on, so the relay contacts can only be closed when the ignition is on.
In the same way, it turns off the electric fan if the temperature at the bottom of the radiator drops below 84°C.
The illustration shows the fans of a 4-cylinder engine with a reinforced cooling system. It functions as follows: the cooling fan itself (2) drives a second cooling fan (1) with a small V-belt.
With a 6-cylinder engine, a two-speed fan is in place of a similar design. Vehicles with enhanced cooling systems are equipped with two two-speed fans, each with its own drive.
The cooling fan thermal switch on 4-cylinder and 6-cylinder vehicles is located on the radiator at the bottom left.
Additional resistors for the two-speed cooling fan are located slightly below the left headlight. In the illustration, the arrow indicates the resistor board with the shock absorber removed.
If the temperature of the water in the lower part of the radiator has risen by more than 99°C, then the second stage of the thermal switch starts to work, switching the second stage of the fan speed through cell 3 (on relay carrier 1). Disconnection occurs, as in the previous case.
Fan thermal switch switching temperatures
Enabling auxiliary fan 4-cylinder 85 kW and 5-cylinder engines
In models with a 4-cylinder engine with an output of 85 kW and a 5-cylinder engine, the cooling system is supplemented by a so-called series fan.
Such a system functions as follows: if hot air stagnates in the engine compartment after the engine has stopped, the cooling system fan provides cold air access. This prevents the formation of vapor locks in the high pressure fuel lines - the cause of problems starting a hot engine. In this wiring diagram, the thermal switch on the cylinder head «feels» temperature in the cylinder head and turns on the fan via the control unit for turning on the cooling fan after the engine stops at the relay socket 1 in the relay rack 1. On models with a 5-cylinder engine, an additional purge fan is installed after the engine stops.
Note: From electrical connection via terminal X (see chapter «Body electrical system») it turns out that the fan of the cooling system - it does not matter, one- or two-speed - when the ignition is off, cannot start working. This is not the case with the 85kW 4-cylinder and 5-cylinder models due to the function of turning on the cooling fan after the engine stops. Here the fan can work even when the engine is off. Be careful!
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