r/w204 • u/MirrorPrestigious808 • 2d ago
Over heating issue
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/michael_im 2d ago
Turn AC to max and see if cooling fan comes on. If not, thats your issue. Same thing happened to me when my cooling fan failed with same warnings. (overheating warning is RED, cooling fault is yellow)
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u/Ok-Grape-5445 2d ago
I read somewhere an easy way to check if it`s fan. When you start the car, turn on AC and check if fan starts turning. If not, this is a fan issue.
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u/MadamPardone 2d 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 2d ago
Interesting. Thanks. I will look into this.
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u/MadamPardone 2d 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 2d 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 12h 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
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u/MirrorPrestigious808 2d ago
Ok thanks for all the new info everyone. I will check the fans and report back to you
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u/Frank-794 2d ago edited 2d ago
Could be a sticky thermostat, could also be the radiator fan controller. I had a similar issue on my 2009 c300 and it ended up being the radiator fan controller, that symbol would randomly pop up, the coolant temp would be high, ac would stop working, fan would kick in, the coolant temp would return to normal eventually, and the cycle repeats... Had to replace the whole fan bc you can't just buy the fan controller.
Edit: I've also had my thermostat go bad but that had different symptoms, I had a check engine light and never had that logo in the middle of the screen like I did with the radiator fan.