Q: Car Temperature Rising

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Hi, my gauge in my 2009 Wrangler increases when the car is in idle (usually after 10-15 minutes of running), once I start driving again it decreases back down to normal. I have also noticed a decrease in my heat inside the car during that time it's in idle. Would you say it's the Thermostat or Radiator?

My car has 110000 miles.
My car has an automatic transmission.

You should first confirm that the temperature controlled radiator cooling fans are functioning. If they are not working, or not working well, that would cause overheating at idle. The only way to condemn a radiator, other than if it is obviously leaking, is to flow test it. If the engine temperature while driving is in the normal range, the thermostat is probably OK but thermostats do go bad with age and anytime you open the cooling system up to, say, replace the water pump, it’s always a good idea to install a new OEM thermostat (not aftermarket, but rather OEM). Other relevant causes of overheating are low coolant level, a faulty radiator pressure cap, collapsed hoses, and a faulty water pump or drive belt. Certain engine faults, such as a leaking head gasket (not likely in your case) or poor engine running condition can also cause overheating. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine overheating diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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