Overheating when A/C on?

2010 MERCEDES BENZ S550
119,280 MILES • 5.5L • V8 • 2WD • AUTOMATIC
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MRJTWATER007
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  • 1 POST
The car runs at a normal temperature without A/C on holds steady around 80-90 degrees Celsius. Once I turn the A/C on, after about 5 minutes the temperature starts to rise and will continue to rise until the car says stop driving high coolant temperature. It does not run hot if I am on the highway with the A/C on and holding a steady speed around 70 MPH but once I start stopping at traffic lights it starts to overheat. I changed the thermostat it didn’t do any good. Can you tell me what might be my problem?
Sep 27, 2024 at 7:50 PM
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STRAILER
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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Sure, can I ask if the cooling fan is running while the A/C system is on? If not, this will be the problem. If the fan runs your problem has an internally or externally clogged radiator. Please go over this guide to see what I am talking about:

https://www.2carpros.com/articles/engine-overheating-or-running-hot

If the cooling fan is not working, I would check the #5 100-amp fuse in the fuse panel under the hood. If the fuse is good and the fan is not running, I would replace the fan motor, which is a common failure.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the images (below). Please let us know what happens.
Sep 28, 2024 at 11:21 AM
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