Overheating Engine, NEED HELP. The mechanic can't even find the cause...

Asked by Aug 06, 2011 at 02:35 AM

Question type: Maintenance & Repair

When driving on the freeway for any length of time, the engine really starts to run hot when the a/c is on. Nearly up to the red. My mechanic thought it might be a fan or a sticky thermostat. $220+ later, it's doing the same thing again. It doesn't do it on short trips, only when I'm on a freeway. If I shut the a/c off it cools down. On surface streets, I can run the a/c the entire time and the temperature stays about midway on the guage. Any ideas? Most of my driving will end up being on the freeway so I can't let this go and just drive on surface streets. My mechanic can't seem to figure out what's causing it and he hasn't been able to reproduce the issue. I can't keep taking it back in at $200+ per pop. Any advice or guidance would be helpful.

3 Answers

65

could be a bad belt (loose or otherwise not 100%) compressor is not at 100% running condition, compressor bearing.

65

compressor is bad, belt is bad too loose/worn, oil in the freeon is low or totally out (134a or R12 depending on year of car) bad compressor bearing the obvious low coolant levels, thermostat stuck, coolant pump sticking/seized, fan thermostat hope that helps pease let me know

1,695

it could be the fan itself...the electricity that activates the fan might be okay but the fan mechanism itself maybe busted or short circuited..new model cars today rely on electronics to tell if the radiator is overheating, so at a peak temperature the computer tells to activate the fan then shut off again when its cooled down...if that heat sensor is busted, you should check your computer box or even the fuse...it could also be possible that your radiator hose is clogged or the radiator has blown so its loosing coolant fastsame thing happened to me before...the best remedy is, change your radiator and your fan...bet a twin row ceramic radiator instead of a stock single row radiator made of aluminum, it circulates water better and is less succeptible to pressure...

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