When you say overheating, are you talking about it going into the red on the gauge? or just losing fluid out the over flow? I am staying at 180 to 200deg, however my message comes on low fluid level, add about 1/8 0f a gal antifreeze and it is good for awhile. This seems to happen mostly when I turn the A/C on an the temp outside is 80 or higher. Any feed back ?