Q: My car starts to run hot if I cannot maintain a consistent speed where air is moving across the engine.

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My car has started to run hot when I cannot maintain a consistent speed where air is moving across the engine. This is especially true in the current hot weather. If I am on the highway and moving I am fine, the temp stays in the normal range but if I get into a situation where I am stopped in traffic or at a red light and no air is moving across the engine, the temperature gauge starts to creep up towards hot. If I turn my A/C off, that helps right away or if I start going again and get air movement the temp comes back down. What is causing this? Is my thermostat going bad? How much does that cost to fix?

My car has 185700 miles.
My car has an automatic transmission.

Hey there, your car has an electric cooling fan. It should start automatically when the engine gets to a certain temperature or when you switch the A/C is on. In hot weather with the A/C on, the fan should switch to a higher speed. If the fan is not coming on, or is switching to high speed with the A/C on, that would cause a run hot condition.

Here is a simple check: open the hood and start the car with the A/C off. Depending on the temperature, the electric fan on the radiator should not be running. Switch the A/C on. The fan should come on within 30 seconds if it is hot outside. If it does not, then it could be a bad fan relay or temperature sending switch. The cost of repair will depend on the part that is faulty. If you need help having this checked, a certified professional from YourMechanic can inspect the slight overheating issue and make adjustments to prevent further issues.

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