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AC question ??

4179 Views 12 Replies 6 Participants Last post by  Richard
In my 2010 Malibu with the air delivery mode control set to Vent, and the recirculation mode set to outside air, and the AC switch set to off the AC unit is off. When you press the recirculation switch to inside air the AC compressor comes on and can not be turned off unless you go back to outside air. Is this normal ? The light next to the AC on switch is not on. My car does not have automatic climate control.
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Yes, this is how the vehicle is supposed to operate. Setting the air controls to "recirculate" always turns on the AC.

Also, turning the defroster on runs the compressor as well.
Correct, and there's a reason for this. If you set the control to recirculate and the compressor didn't run, the air in the car would become stale very quickly and you would get quite a bit of fogging. Without the compressor running, you need to draw in outside fresh air to minimize this. In recirculate, the air can become stale and stuffy even with the compressor running. Without the compressor, it would be magnified much more.

I only use recirculate to avoid outside odors (exhaust fumes from a bus) or to cool the car quickly on a very hot day. You will notice that the air is colder when you run the A/C in recirculate mode. I always switch to outside air soon after.
Why does it become stale and stuffy when recirculating less with the compressor though? I don't follow that but did know that it comes on, of course.
Because the compressor dehumidifies and freshens the air, that's why it's forced on when you hit recirculate. But, when you use the outside air, it forces in fresh air and pushes out stale air. That's why you don't want to use recirculate for long periods of time. It's literally doing what it says - it's recirculating the air from inside the car. It's not utilizing the car's flow through circulation system. So over time, the car will feel humid and the windows will fog. The compressor improves this to a degree, but not for extended periods of time. Without the compressor, the air quality in the car would be very uncomfortable in a short period of time.
I noticed something with the Malibu A/C that's not a problem, just something to point out. It's very hot and humid where I live and if I'm sitting in the car waiting for someone, I run the A/C. I noticed that the A/C drops a massive amount of water compared to other cars I've owned. Today, I ran the A/C for 5 minutes while idling and there was a flood of water running from under the car. It was so much you almost think something is leaking, but it's just condensation from the A/C system. Not a problem. I just never saw this much water run off from an A/C system. But it has been extremely humid, so this can add to the water that's being extracted.

Has anyone else noticed this with their A/C?
I was just surprised to find it running the AC when it isn't logical to do so, at least not to me. I wish there was a way to reach in and reprogram those BCMs - I'd do it in a flash!
Beyond what I said above, there's probably saftey issues with running the compressor in recirculate. If fumes got drawn into the car and you hit recirculate, you're not utilizing the cars flow through circulation system where fresh air is drawn in and the fumes are pushed out. As I said, the compressor freshens the air thus reducing the fumes. Without the compressor running, you can be overcome by CO. Also, they don't want to create a situation where the windows would fog very quickly - and they would if the compressor didn't run. This could obstruct your vision.

If you look at it from this perspective, it sounds very logical to run the compressor.
Not arguing with you, Richard, just ranting about GM's move to take options away from me. It didn't use to be this way in the past but it looks like it's here to stay. Drat, and double drat!
No argument, just a discussion. I would think (& hope) that something like this is well thought out by the GM Engineers.
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