Page 1 of 2

Time delay on AC cut-in after start

Posted: Mon Mar 07, 2016 6:22 am
by elc32955
It came to mind when I was realigning the topics earlier tonight that I had neglected to create a forum for heating, AC, and vehicle cooling topics, so here it is! I'll kick this one off with a first post.

When starting my car, there's sometimes a very long time delay between the time the car starts after I turn the key and the AC turning on. I've experienced delays before of between 2-4 minutes (on the long end, many times shorter) before the AC compressor will start and the vehicle will begin to cool. Granted it's March, but here in Florida (as with many of the southern states) it gets bloody hot and humid, and the time your car is running and pumping hot, humid ambient air in your face before the AC kicks in seems like a lifetime. Is this a common bug and has anyone else seen this?

Thanks
Eric

Re: Time delay on AC cut-in after start

Posted: Mon Mar 07, 2016 11:38 am
by storm9c1
No, I haven't seen this myself. But it could be low freon pressure in the system. Have it checked with a manifold set or check it yourself. Using a real A/C manifold set is the only way to determine this, not one of the cheapo low-side gauges from part stores. Harbor Freight sells an inexpensive manifold kit. I have two if them. LOL.

Re: Time delay on AC cut-in after start

Posted: Tue Mar 08, 2016 1:08 am
by 9C1fanatic
I have seen the opposite problem on both my new 14 caprice and my work 14 caprice. The compressor will sometimes run for several minutes even after you have turned the AC button off. I figured there is probably some rhyme or reason to this programming. I am going to assume the AC is probably controlled by a combination of the PCM and BCM.

Re: Time delay on AC cut-in after start

Posted: Tue Mar 08, 2016 10:06 am
by CrashTestDummy
Could it be that the temp sensor in the car is sensing a cooler temp that what is set on the controller? Or, there's a delay in the controller getting a signal from the sensor? That would be what I would think is happening, but it's pure speculation.

The issue I have with our 2012 is EVERY time I turn the system on, the compressor is on. That's even after I turn it off in the previous drive. And it's no matter what the outside temp is. When I press the power button, I then have to press the 'snowflake' button if I don't want the A/C on.

Re: Time delay on AC cut-in after start

Posted: Mon Sep 05, 2016 12:43 pm
by PPV4ME
Mine does this almost every time, and I just had it topped off to the proper pressure by a shop. Strange issue.

Re: Time delay on AC cut-in after start

Posted: Mon Sep 05, 2016 2:09 pm
by xcidmigs
I have no delay on my 2011 just takes a minute to get up to full blast speed and yes its default to turning on the AC every time. My problem is a musty smell that is inside the HVAC case all summer long pretty much, It was less so this summer because i learned the trick of heating it up occasionally and spraying some lysol in as its on recirc mode but apparently its a known G8 issue and has some odd GM fix using a timer switch the runs the fan only when you turn car off.

This is the fix but I'm not sure I'm going to do that to my car.

http://www.g8board.com/forums/4-tech-lo ... smell.html" onclick="window.open(this.href);return false;

Re: Time delay on AC cut-in after start

Posted: Thu Sep 08, 2016 11:50 am
by 9C1fanatic
Have you tried replacing the cabin filter to see if that helps with the smell?

Re: Time delay on AC cut-in after start

Posted: Thu Sep 08, 2016 7:08 pm
by xcidmigs
9C1fanatic wrote:Have you tried replacing the cabin filter to see if that helps with the smell?
yes I have, its about a year old now, and that has nothing to do with the issue, apparently this is a GM design flaw across numerous platforms such that they came out with the electronic timing device that just runs the HVAC blower fan for a few seconds in an attempt to dry out the inside of the AC box where the mold spore tend to grow in certain climates. I guess I win with our crappy super humid NE summers... I just forgot to do the trick of running the blower with AC off on way home last night and this morning got a nice blast of foot smell as i went to work, temps all week in the high 80's with humidity.

Re: Time delay on AC cut-in after start

Posted: Sun Jul 14, 2019 11:01 am
by grummin
Reviving an old topic here but has anyone figured this out? I put gauges on mine and before you start the car I have equal pressures from high side and low side. After I start the car and turn on the AC I can see the compressor clutch latch and spin the compressor but the pressure remain the same on both high side an low for a few minutes and slowly the low side pressure starts to drop and the high side starts to rise until they reach normal pressures for the ambient temperature. From my experience this is not normal and the pressures should got up or down depending on the side of the system as soon as the compressor starts. There is something delaying it from building pressure. I am thinking maybe it is an expansion valve or do these compressors have some kind of variable vane system?

After about 5 minutes everything is normal and the AC is cold. My car is a 2011.

Re: Time delay on AC cut-in after start

Posted: Sun Jul 14, 2019 11:30 am
by Sanford
If I remember correctly, the compressor is a variable displacement that is electronically controlled. I have a 2011 that will start blowing cool air after about 30 seconds run time and will cool the car off in the morning. After the car sits out in the sun all day in the mid 90's, it blows hot air for a couple of miles driving and then it will start blowing cool air, not cold air. It acts like the compressor clutch is not engaging, but it is. I replaced the high side charging port and added an ounce of PAG oil and it did not seem to make any difference the way it acted. My next thing to try will be to replace the expansion valve, but I have a gut feeling that there is a compressor problem. Since it is my one of my work cars, I am in no big hurry to solve the problem.

David