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Q: Overheating.

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i recently changed my water pump and thermostat and my car is still overheating. i can still drive it just not for long, it doesnt get in the red but it jumps up there. what could be the issue?

My car has 9000 miles.
My car has an automatic transmission.

It sounds like you may have a faulty coolant fan switch. The coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. The typical electric cooling fan circuit includes a temperature sensor, a relay, a control module and the fan motor. The relay is the component that fails most often, so be sure to test the relay as well as its power supply and ground connections. A good relay coil will typically read 40 to 80 ohms. If resistance is high, the coil may still be working but it is failing, or it may not work when electrical loads are high. If the coil has no resistance, it is open and has failed and you will need to replace the relay.

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