Inconsistent Heat/AC

GanderGirl89

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I've been having another problem with my '03 Grand Am. In the winter my heat was very inconsistent. If I had the dial on full heat it would be hot with no problems. However, if I moved it towards cool at all it would be warm, but then all of a sudden it would just start blowing cold air. Didn't matter what setting it was on or anything. If I moved it back to full heat it would be hot again. Now this summer my AC is being inconsistent. I usually have it on full cold if it's on, but it will randomly turn to warm air. To correct I have to turn the dial to warm and then back to full cold. My car has also been running a little hot, also. I hear grand ams are supposed to run at around 206, but mine has been venturing up to around 215 and sometimes 220, but not always. My coolant reservoir is full and my car has not overheated to the point where turning the heat on has not corrected it. Would this be a faulty sensor somewhere or what?
 
On the inconsistant heat/AC the problem could be the blend door actuator motor. On the car running hotter than usual, it is 10 years old and you may need to have the system flushed and replace the thermostat. If you have the V6, there has been an issue with leaking lower intake manifold gaskets. You could have the system pressure tested and visually examined.
 
You definitely want to address the cooling system completely at your earliest convenience, it might save you more trouble and expense later. I have a 96 Gran Am with the 3.1L V6. I've just replaced the entire cooling system with the exception of the heater core which was replaced a few years before.

In my experience, overheating is often a prelude to head gasket failure. My engine started leaking, I erroneously thought it was the water pump which I replaced (easiest water pump replacement I've ever experienced, by the way). The leak was later diagnosed as lower intake manifold gasket as melsg5 suggested.

Soon after that was completed, the engine developed another leak. Yup. Head gasket failure.

All that said, your cooling system may be the most important, next to clean oil, in prolonging the life of your engine.

Cheers! :cool:
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