I'm having issues with my C3 II (2006), Petrol, 1.4, with AC, in which the coolant fan will not come on. I've tried various things and have some follow up ideas, but before doing major work or ordering expensive parts I'd like to double check the reasoning and use some of your collective experiences.
The issue:
The engine coolant fan will not come on, even when reaching threshold temperatures. When sitting in traffic with the engine running I've had various engine temperature warnings, which caused me to stop on the side of the road and let the engine cool off.
What I've tried and tested:
- I've read that turning the AC on should turn the fan on as well. I've ran the car with AC enabled for a solid 10 minutes, no fan movement. The AC does produce cold air.
- I used an OBD2 reader to read the (green) coolant temperature sensor. This produces sane results as I watch the temperature slowly go up as the car idles
- For good measure I disconnected the wire to the (green) coolant temperature sensor, as some videos showed this would turn the fan on. This was not the case, and I observed the reported coolant temperature levels drop to some negative celsius value. Additionally a warning engine code appeared that the reported temperature was out of bounds. To me this confirms good working temp sensor.
- The thermostat is working. I'm feeling hot coolant on the in AND output side of the radiator as the car approaches 90C. I've also observed through the OBDII reader that the reported coolant temperature drops as the thermostat opens, confirming the working of both the thermostat and the coolant temperature sensor
- I learned about the existance of the MAXI fuses, and checked the one in the first position (coolant fan). This one is healthy. Checked both visually and with a continuity test on a multimeter.
- There's also continuity between the MAXI fuse socket and the wire towards the radiator resistor
- Ive tested continuity on the radiator resistor on the fan unit. This reports a working condition. I've also switched it with a new unit and made no difference.
Sadly none of the above tests have shown me the culprit. I have the following ideas left, but would like to hear your thoughts on them:
Coolant fan motor itself died
Could be that the fan itself (motor) died and thus will not come on. I tried measuring resistance on the motor of the fan but due to the angles this was not possible.
I've turned the fan by hand and there is not much resistance there.
Before ordering expensive new fans and/or disassembling the entire unit, is there anything I can do to confirm that this is the issue?
Blue coolant temp sensor?
I read that some C3 models also have a blue coolant temperature sensor. I wasn't able to find one on my model, but before removing the airflow housing I wanted to check if this could in any way cause these issues. If it's relevant, my dashboard does not have a coolant temperature gauge.
Anything I missed?
Open to any ideas that might point me in the right direction.
Many thanks!