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I just noticed that my A/c compressor was running all the time even when calling for full heat. I had my wife hit all the buttons on the dual climate control while I watched the compressor. It finally shut off when she hit the A/c button several times, and now I can't get the compressor to come on again no matter what buttons you press! I checked the A/c fuse (26) and switched out the relay(32) with the horn relay and still no compressor action. What do you guys think might be the problem? Thanks, Bob.

from the first part of your post, it sounded normal. any time the climate control is on auto, the compressor is running. as far as it not coming back on... i'd say if the compressor sounded fine before, it sounds like you have a refrigerant pressure issue. If it gets too low it will prevent the compressor from engaging.

Why would the A/c compressor run all the time with the climate control in auto even in the full heat mode? This would really hurt your gas milage! Right?

Villainville wrote:Why would the A/c compressor run all the time with the climate control in auto even in the full heat mode? This would really hurt your gas milage! Right?

It's designed to keep the oil in the A/C system circulating during the colder months when you're not likely using A/C. At least that's my take on it, all my older cars would run the compressor when I used the defroster. The older cars weren't smart enough to know that I un-plugged the compressor magnet during winter to save gas though

The newer compressors are variable volume, so they don't cycle on and off like the older ones. When in auto, pressing the A/C button once will change the display from auto to A/C on. Pressing it again, it will go to A/C off. If it is cold there, it may not come back on right away, until the temps get up some. It has to be around 40*.

I was told by the dealer tech that the AC compressor stays on all the time when you have the Auto Climate system to control the humidity in the vehicle (fogged windows, etc). In fact, I am almost POSITIVE it says this in the manual as well.

I doubt it will hurt your gas mileage much - newer AC systems are relatively efficient. In fact, it's been proven that driving with your windows down hurts fuel economy worse than driving with your AC on.