Engine Fan comes on and off intermittently

[x3L2004]

I’ve been driving to work which is 3.5-4hrs daily for about 2 weeks now and today on my way back I noticed the fan keeps coming ON and then OFF. Maybe every 10 seconds it would do this. The temperature gauge is normal so I’m wondering if it’s a faulty thermostat ? Any way to diagnose this at home ?

Vehicle is a 2013 F30


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[RBNetEngr]

It wouldn’t be a faulty thermostat, since the fan is turned on/off by a separate coolant temperature sensor. So, it’s possible that the sensor is having issues.

Another possibility…your AC refrigerant is low, so the AC compressor cycles on, low pressure in the refrigerant is detected, so it shuts off. And the cycle repeats. When the AC system turns on, so does the electric fan in front of the radiator.


-rb

[x3L2004]

It wouldn’t be a faulty thermostat, since the fan is turned on/off by a separate coolant temperature sensor. So, it’s possible that the sensor is having issues.

Another possibility…your AC refrigerant is low, so the AC compressor cycles on, low pressure in the refrigerant is detected, so it shuts off. And the cycle repeats. When the AC system turns on, so does the electric fan in front of the radiator.


-rb

Hmm ok I see. What if my A/C is not on? The fan comes on intermittently even when I’ve turned off heating and cooling in the car. Coolant thermostat seems more plausible …

Any other ideas ?


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[R Shaffner]

Sure.

1) Make sure the system is properly filled with coolant and bled of air.
2) Make sure the front of the radiator is clean and clear (not blocked with debris).
2a) Make sure the viscous fan is working properly.
3) Look for a loose wire or connection in the switch wiring and the fan circuit.
4) Do more testing to see exactly how it's behaving and misbehaving.

For example, open the hood and start the engine with the AC off. Have someone turn on the AC to max cooling. After a few seconds you should hear the fan and compressor click on and stay on. If the compressor clicks off and on, check the AC fill and system. If the compressor stays on while the fan click on and off check the fan and circuit.

5) Test the switch and the fan and the fan relay.

[x3L2004]

Sure.

1) Make sure the system is properly filled with coolant and bled of air.
2) Make sure the front of the radiator is clean and clear (not blocked with debris).
2a) Make sure the viscous fan is working properly.
3) Look for a loose wire or connection in the switch wiring and the fan circuit.
4) Do more testing to see exactly how it's behaving and misbehaving.

For example, open the hood and start the engine with the AC off. Have someone turn on the AC to max cooling. After a few seconds you should hear the fan and compressor click on and stay on. If the compressor clicks off and on, check the AC fill and system. If the compressor stays on while the fan click on and off check the fan and circuit.

5) Test the switch and the fan and the fan relay.

Thank you for the suggestions! Will update on the fix and issue.


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