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HVAC Question - AC Compressor

W

wrchism

Charter Member
SM 2004
SM 2003
Full Member
Joined
Feb 21, 2002
Messages
1,339
Location
Greeley, CO
The Av's A/C works great - one question though. We'd been driving during the day with the A/C on - left it on, shut down the engine. Went out later, cranked it up, and sure enough the A/C light is still lit - as it should be. But, it's cooler now - so I push the A/C button to turn off the compressor. As far as I could tell, the compressor did not drop out - air still very cold out of the vents. Later that night started it up again - now the A/C light is off on start up - and the air feels like outside air - a bit warmer and noticably more humid.

Anyone else experience this? I know a number of years ago, GM A/C systems were set up to keep the compressor on until engine shutdown, but I hoped that wasn't the case with the Av.

May be time for some experimentation with the hood up!
 
My A/C compressor will continue to run with the A/C button "off" and the recirculation button "on". Dealer told me this was normal. I was advised to only run recirculated air "on" when A/C button was "on".

Sounds funny but two dealers said the same thing so I believed them.

 
Thanks for the reply. ?Running recirc air with A/C makes sense - except when you first get in a hot vehicle, the air inside is cooler than that outside - recirc is more efficient. ?In fact, the Av manual says that the system will automatically switch from outside air to recirc if the A/C load becomes too great - don't know how it senses that, but that's the claim. ?

I'll try switching from recirc to outside air to see if that drops out the compressor . . don't think that detail is in the manual.

Thanks again - and welcome to the site DevilDog! Give us some stats on your Av!
 
I have a good one: I have noticed that when I have the Av in Park (let's say my wife ran into the store and I was waiting for her), the Air is on. But suddenly it seems that the compressor shuts down because the air gets warm. Has anyone noticed the same thing? Or is this a problem/defective compressor? The air blowing shouldn't get warm if the Av is in Park, but still running. Correct? Should I have this checked at the dealership?
 
Prince . . .

At idle, you don't get the cooling that you do on the road, but that's sort of subtle. ?I'd ask the dealer - who knows what tricks are incorporated into the Av's "Big Brother is watching you" computer.
 
hey Prince,
I'll bet you have the automatic climate control type and you have the temp set at say 75 and you don't have the fan control on auto, you have it on say 1/2 way.
so, like at home, when your a/c has reached 75 the compressor kicks off and since the fan is not in auto it will keep blowing at same speed only with out the compressor running it is noticeably warmer.
When that happens again try to turn down the temp ( to say 70) and see if your compressor kicks back on.
Good luck,
Damon
 
Thanks for the replys. I'll hav the dealer check it out tomorrow. Damon, I don't have the Auto Climate control option. I can hear it cycle off, then it just blows hot air. But only when I'm sitting for an extended period (doesn't do it at redlights).
 
Mine did the same at idle i hooked it up too gauges and i let a little freon out and that seemed to help, 134a is very easy to overcharge since the is no sight guages anymore!!
 
DEVILDOG said:
My A/C compressor will continue to run with the A/C button "off" and the recirculation button "on". ?Dealer told me this was normal. ?I was advised to only run recirculated air "on" when A/C button was "on".

Sounds funny but two dealers said the same thing so I believed them.
Click to expand...
I was told that the compressor is also used to dehumidify the air that passes through it whether it is actually cooling or not. This story seemed to hold up when I noticed that blowing HOT air on the windshield (defrost) ALSO made the light on the AC button come on. So in that mode it appears that it's using the compressor to dehumidify the air so that it defogs the inside of the window quicker.

In purely "recirculate" mode I think it's taking moisture out of the air from the passenger's breath. There's a lot more there than ya realize until you go parking and try to figure out how to clear them to head home. :)


 
TXAVy said:
I was told that the compressor is also used to dehumidify the air that passes through it whether it is actually cooling or not...
Click to expand...

I'm not even going to pretend that I know exactly how the A/C systems work in your Avs, but my understanding has always been that the compressor is used for defrosting the windshield only in southern, humid, warm states and that it does not come on in vehicles sold in northern, colder states. This always sounded strange to me, but makes some sense if you understand general A/C principles and think about it for a moment.

Maybe this has been changed for newer, more sophisticated systems; I'm sure someone here knows.
 
All auto A/C systems require a compressor . . whose purpose is to cool the evaporator coil in the HVAC system. This cold coil both cools and dehumidifies the air. Defrost generally defaults the compressor 'on' unless the temperature is too cold. This dehumidification helps to clear fogged windows much faster.
 
New to the group, howdy all AV lovers. My experience and my question really is that MY compressor seems to be on ALL the time the fan is on. I can shut off the AC button and the compressor will continue on it's merry way. Whether it is 50 degrees or 100 degrees. In VENT or DEFROST mode. Of course when I really need the defrosting capabilities of compressed air like when it is snowing and the window is fogging up, THEN it doesn't seem to come on no matter what!
 
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