How to check the radiator fan for the engine

Contents

How to check a mechanical cooling fan

Check the cooling fan drive belt.
Replace the belt if you find any oil residue on it. If you notice any signs that the drive belt is snapping or worn, replace it.
Check the drive belt tension and the condition of the idler pulley.
Check the radiator fan bearing.
Turn off the engine and spin the fan by hand. It should rotate smoothly. Replace the bearing if the fan does not spin freely or you notice runout. Some bearings require replacement of the entire assembly.
Tighten the belt if there is play.
Replace the tensioner pulley if it is defective.
Check the fan viscous coupling
With the engine off, rotate the fan blades and check the axial play . There should be no resistance, inertia or backlash.
If you spot these signs of a defective fan viscous coupling, remove the part. Heat the clutch by placing it in boiling hot water for at least 10 minutes. Carefully remove the heated part and try to give it a few spins.
If you don’t feel increased resistance during the second spin attempt, add silicone oil to the fan’s viscous coupling. If the fan’s viscous coupling is maintenance-free (i.e. it cannot be refilled with silicone oil), replace it.

Caution! Always remove the negative battery terminal before checking an electric fan.

Check if the fuse is blown. If so, replace it.
Check the relay.
Replace it if you see soot or oxidation on it.
Check that the relay is working properly.
Check the relay and fuse diagram. Find the cooling fan relay and its resistance rating.
Connect the multimeter to the cooling fan relay and check the actual resistance value.
If the actual resistance value does not match the nominal value, replace the relay.
Check the radiator fan wiring.
Replace the wiring if damaged.
Check the coolant temperature sensor.
To do this, start the engine, allow the coolant to warm up to 80-95°C and check if the fan has started.
If the fan has not started, replace the coolant temperature sensor.
Check the Connectors.
If the connectors are oxidized, treat them with electrical contact spray.
Turn on the fan to check the operation of the electric drive.
Disconnect the binding posts from the temperature sensor and start the engine – the Fan should now work.