Engine Cooling problem
2004 Kia Optima 4 cyl Two Wheel Drive Manual 83,200 miles
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My car keeps trying to overheat. It never has but it gets almost in the red everyday. When I turn off the AC it will go down a little...but it is hot in Louisiana and I need my AC. The AC does work fine, it just makes my car to run hot.

Hi there,

Time for a full cooling system service. Replace the thermostat, have the radiator cleaned & flow tested, check the pressure cap & flush the old coolant. Make sure that the fans are working (two) with the A/C on as well.

Mark (mhpautos)

It sounds as if we have virtually the same problem: almost overheating 80K 2004 Optima with ac on. I've tried almost everything: new water-pump, new thermostat, radiator flush, verified hoses not collapsing, verifiying both fans operational. I'm going to lean-out the anti-freeze from 50% to the 35% minimum recommended and see if that works. Please post to your site if you find anything. Thanks. Doug

I had an intermittant indication of overheating with my Optima. I tried everything to isolate the problem: new water-pump, new thermostat, radiator flush. However, when the needle approached red, and I turned off and turned on the engine again, it would show normal. This turned out to be an electrical problem, and was eventually isolated to (you're not going to believe this) A LOOSE NEGATIVE BATTERY CABLE!

Hi dougesego,

Thanks for the in put. it all helps. This is a good example of looking at all the possibilities and keeping on top of basic maintaince issues, modern cars and the electrical systems are a pain at the best of times, but a simple problem as a loose or dirty terminal can sure through a spanner in the works.

Mark (mhpautos)