Control of Engine Cooling Fan

The engine cooling fan is controlled by the engine control module.

The Following Components Affect The Control Of The Engine Coolant Tan:

^ Engine speed sensor (1), giving the engine speed.
^ Engine coolant temperature sensor (2), giving the engine temperature.
^ Speedometer (3), giving the vehicle speed.
^ Dashboard controls (4), for the air conditioning system (A/C on/off).
^ Air conditioning pressure sensor (5), gives the pressure in the air conditioning system.

When extra cooling capacity is required, the engine control module (6) activates fan relay (7) and engine cooling fan (8) starts.

The engine cooling fan is activated if engine coolant temperature exceeds normal operating temperature (102°C (215.6°F)).

In Cars With Air Conditioning The Engine Cooling Fan Is Also Activated If:

^ The air conditioning system is on, vehicle speed is low (below 65 km/h (40 mph)) and pressure is above a set limit.
^ Pressure in the air conditioning system is too high.

When The Engine Is Switched Off The Engine Control Module Can Keep The Engine Coolant Fan Activated As Follows:

^ For 6 minutes if engine load and temperature have been high before it was switched off.
^ For 3 minutes if the fan was running at high-speed before the engine was switched off - there is a risk of overheating.

The engine control module has two speeds. Low-speed is used for normal control. High-speed is only used if there is a risk of the engine overheating or if pressure in the A/C system is high.