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Temperature gauge

I have a car with a temperature gauge that sits at about 1/3 until I put the A/C on when when idling the gauge rises quickly to the red. However, it does not do this when driving around the city, or better on the highway. It will rise very slowly upwards when idling for a long period of time without the A/C on. Southern Indiana b.t.w. in Summer. Any suggestions from Car Novice.

Your radiator could be PARTIALLY plugged or your electric fan may not come on at the right time. I would have a knowledgeable shop do some testing to pinpoint the problem.

You have two fans, one energized when you put the AC on and the other by a temp sensor. Since it’s rising fast with the AC and slowly without, I’d be inclined to suspect Doc’s suggestion of a partially plugged radiator, or perhaps a partially stuck thermostat or collapsed hose liner.

Or both fans are toast. Sometimes when two fans are both in the same plastic shroud and one overheats and melts the shroud the melted shroud physically interferes with the other fan. I once had a shroud melt like you would not believe.

But, I agree that this needs a shop look-see.

Check for proper amount of fluid in the reservoir and radiator, check that system is holding pressure. Start simple and work your way up. Be sure to read all precautions about checking radiator level.

Thank you so much! Since you all suggested the same, I will take these ideas along and have it looked at, praying it does not cost too much!