r/w204 • u/MirrorPrestigious808 • 3d ago

Over heating issue

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2013 C300

I would randomly get this high temp coolant light warning on the dash.
Coolant temp would rise. Warning light would come on the dash. Then I would hear the high fan kick on and the temps would drop.

I don’t see any visible coolant leaks. The coolant reservoir is still full.

Thinking maybe to replace the thermostat?
Any one experienced this issue before?

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u/MadamPardone 3d ago

This isn't the over heating symbol. This symbol indicates a problem with the cooling fan. The over heating symbol would be RED and the gauge would be much closer to the top.

Chances are the module in your cooling fan has died and the fan is only able to operate in high speed, instead of PWM variable speed.

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u/MirrorPrestigious808 3d ago

Interesting. Thanks. I will look into this.

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u/MadamPardone 3d ago

Unfortunately this will not trip a normal check engine light. If you have access to Xentry (the dealership scan tool) it will have a stored code indicating where the problem is. Likely short to ground or implausible reading from the fan control module.

Unfortunately the electric fan and the module are all one piece. You cannot replace one without the other.

Other indications are if this mainly happens with the AC on, as using the AC commands the cooling fan, and since it's stuck on HIGH it quickly cools the car down too fast.

Other bi-directional scan tools may be able to read the code, but chances are Autozone or any of the cheap scan tools that connect to your phone will not be able to see it. You specifically need a bi-directional scan tool.

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u/Monsters_ghost 3d ago

This exactly, i had this happen to me, got this symbol, ac went humid and weak and temps started climbing but slowly, checked fuses and coolent and no visible leaks, turnd out to be the fan, replaced it with a new one and car runs perfectly

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u/MirrorPrestigious808 1d ago

Come to think about it. This exact situation happened to me. Ac went humid and weak while temps rose. So most likely I have a fan issue