AC Question

[RayYork]

Please forgive me if this has been discussed before but I couldn't find a thread that addressed this specifically.

I just got back home (north of Seattle) from a road trip to the SW (CA, NV, AZ, UT). My car has neer seen +80 degrees until this trip so my exposure to how the car runs with the AC on has been limited.

While driving in LA, in traffic (100+ deg), I noticed a sound like a hydraulic pump that was low on fluid. The sound would match the speed of the revs of the motor but initially it sounded like it was coming from the transmission (my car is a 2011 2SS/RS M6). I also noticed that my acceleration was labored.

We eventually drove from LA to Big Bear. The power felt weaker than I expected but I was pulling away from my buddies 392 Challenger so I guess it wasn't that bad. It just didn't rev as freely as I am used to. I assumed that it was altitude that was working against me.

The next day we went down to RT 66 and the temps were very high again. We were cruising at high rates of speed and doing well but at one point we missed a turn and need to pull a U-turn on 66. When I did that, I noticed the motor felt like I dropped anchor it was so labored. The noise has continued on an off this entire time and the AC has been on. I killed the AC and the car ran great! Problem was, it was 110+ Deg and we were in the middle of nowhere. After a while the heat got overwhelming and I went to turn the AC back on, well, no love, it would not turn back on!!!

We left 66 and diverted to Las Vegas. I took the car to Findlay Chevy the next morning and guess what....... The AC came on just fine and "there was nothing wrong". The checked the codes and compressor and nothing...... They discharged and re-charged the system and found that a system software update from earlier in the year had been installed but not applied properly so they redid the update.

After leaving Vegas, the system worked fine, in that it blew cold air and continued to work but the noise continued and and the pull on the motor was noticeable.

I am back in WA now and the temps are in the 60's and 70's and I'm at sea level so the system is not taxed nearly as much so the symptoms are not present and my dealer will not be able to replicate the issue.

After this long dissertation, what I want to know is, is this normal for folks that live in high temps and high altitudes? Do I have a faulty compressor? Feedback would be appreciated.

[1BADLS3]

Also from the Seattle area and had a similar experience with another car.

The high air temps and elevation can affect vehicle performance. I drove a Chevy Colorado from Seattle to almost Wyoming in a mountainous area up around 5,000'. The truck was really struggling as the temperature was right around 100 degrees. I mean, it didn't have a lot of power to begin with, but it was really breathing hard, almost to the point where I thought there was a problem. I could feel the A/C compressor kick on and off..When it was on, it felt like I was suddenly towing a boat. The road ended and the trail began. That's when I kicked off the A/C as it was time to crawl in 4-low up the mountain, to an elevation of right around 8,500'. Insane.

I've owned a number of GM cars and the compressors can make noise. also, a second cooling fan usually kicks on, adding more noise, and then I believe the condensors have the ability to make noise as well.

If you think it's a problem, run it on one of these warm-sunny post July-4th days here in Seattle and take a video of it if the problem replicates.

[Ringo64]

Well I can't say anything for high altitudes but I normally always run with my AC on down here. The difference between having your AC on vs off shouldn't be drastically noticeable but there is most definitely a difference.

I would suggest to keep an eye on it. Thing I've realized about AC is it can be really finicky

[Kent2010]

Here in Las Vegas, we've had 100+ deg temps daily. No noises, no labored acceleration from my SS.

Keep in mind that the AC compressor takes less than 10HP (probably more like 3-5hp), so if you are feeling a severe drop in power, there's something else going on, *especially* if you are also hearing strange noises at the same time.

[ckaram]

I've noticed a "whine" with the air on that moves with RPM's, but no significant drain in power.

Interesting that I've just noticed it since it's been over 90*.

Just drove 4 hours with the air on from Detroit and no issues.

[dianeokie]

Many, many threads in the issues thread about the AC. Had my compressor replaced three times before they got it right! Works now!:(

[Obzen]

There was also a reprogram TSB for the 2011's. It had to do with the A/C randomly not working. Sounds like maybe it wasn't done on your car. I'd check. It takes about 30 minutes for the dealer to reprogram.

See here:
http://www.camaro5.com/forums/showthread.php?t=151948

[HorsePower-Freak]

Originally Posted by Obzen

There was also a reprogram TSB for the 2011's. It had to do with the A/C randomly not working. Sounds like maybe it wasn't done on your car. I'd check. It takes about 30 minutes for the dealer to reprogram.

See here:
http://www.camaro5.com/forums/showthread.php?t=151948

Great now I'm worried lol

[edgehead2000]

I just finished a round-trip from Albuquerque, NM, to Vegas and had no AC issues in a 2010 SS.

A friend of mine from Maupin, OR, said that when he brought his Honda Civic from sea level to mile high that he also lost power. He had a tune and fluids changed then it was normal again he said. Maybe pressure related?

[RayYork]

The Findlay service writer said that there was a difference in the pressure when it came in and when they recharged the system. I sent this to my local dealer and am waiting to hear what they say.

[Scalded Dog]

one note, the reason that your AC wouldn't come back on at one point during the day MIGHT be frozen lines. I am told by my ASC certified friend, who specializes in AC, that some parts and lines and hoses and whatnot can occasionally freeze up, rendering the system inoperable. Later, things thaw out and resume operation, like the miracle the day of your AC working just fine at the dealership the following day.

Just a possibility to consider... and I've got no idea how that might tie in with the loss of power issue.

[JohnnyBfromPeoria]

5280' elevation/mile high = 20% lower atmospheric pressure = 20% less power.

John B.

[edgehead2000]

Originally Posted by JohnnyBfromPeoria

5280' elevation/mile high = 20% lower atmospheric pressure = 20% less power.

John B.

I tend to believe this after many a trip between NM and Vegas; in Vegas, I could roll the SS and my old Crossfire off the line by just letting go of the clutch whereas in NM I need a little bit of gas to do the same.

[tomlink]

Can't speak to the power loss, but AC systems have a "recovery mode". If you flip the system off and then back on, recovery mode prevents the compressor from coming right back on to prevent system damage. I'm not sure if this applies to your car though.

[JohnnyBfromPeoria]

Originally Posted by edgehead2000

I tend to believe this after many a trip between NM and Vegas; in Vegas, I could roll the SS and my old Crossfire off the line by just letting go of the clutch whereas in NM I need a little bit of gas to do the same.

I used to live in Albuquerque, at Wyoming and Candelaria, back in the late 80's. Loved it there. I lived there when a guy comitted suicide by renting a plane and flying it into the sheer face of Sandia Peak. Wow.

My cars were considerably slower at altitude (still are), but at least everyone else's power was off by the same measure. Back in those 'olden times' I would re-jet the carb with smaller main jets, as the fuel requirement is less to get the same mixture as at lower altitudes.

John B.

[JohnnyBfromPeoria]

Originally Posted by tomlink

Can't speak to the power loss, but AC systems have a "recovery mode". If you flip the system off and then back on, recovery mode prevents the compressor from coming right back on to prevent system damage. I'm not sure if this applies to your car though.

This is accurate. The compressor is not designed to activate right after it has just shut off. The high pressure side of the system slowly reduces pressure just after the compressor shuts off, which is why you still have cooling even when it's not running (for a short time). If the compressor were to activate, it would virtually run into a walll of high pressure at its discharge point and load the compressor too much, causing damage or a big shock to the clutch/belt/etc.

John B.

[Chevrolet Customer Svc]

Originally Posted by RayYork

The Findlay service writer said that there was a difference in the pressure when it came in and when they recharged the system. I sent this to my local dealer and am waiting to hear what they say.

Please let us know how everything has gone for you at the dealership. We hope everything works out for you. We are also here if you have any questions at all!

Brandon
Chevrolet Customer Service

[RedRaven]

I agree witht the altitude/pressure theory. Next time try the fuse pull when you get to altitude.

Used to have a '85 stang II that came from Colorado Springs. Never ran right in Fla.

[2SS-11]

Originally Posted by ckaram

I've noticed a "whine" with the air on that moves with RPM's, but no significant drain in power.

Interesting that I've just noticed it since it's been over 90*.

Just drove 4 hours with the air on from Detroit and no issues.

Same here, just noticed the slight whinne with air on and high outside temps. Don't remember it from last summer though

[Scalded Dog]

Had an '82 Camaro with a v6... rated for 102 scorching hp under optimum conditions. Drove that thing to the top of Pikes Peak in Colorado, which rises to over 14,000 ft. elev.

Let me tell ya.... I had that ol' thing floored, and it just barely made it to the top of the mountain... very slow, quite a struggle. Had to keep checking my mirrors to convince myself that I was NOT towing five other cars and boat anchor, because it sure felt like it!

[Chevrolet Customer Svc]

Originally Posted by 2SS-11

Same here, just noticed the slight whinne with air on and high outside temps. Don't remember it from last summer though

If you are having a concern with your vehicle, the best thing to do is to get a proper diagnosis by your dealership. This may be something that could be covered under warranty if found to be a defect. Please let me know if you have any additional questions.

Brandon
Chevrolet Customer Service

[2SS-11]

Originally Posted by Chevrolet Customer Svc

If you are having a concern with your vehicle, the best thing to do is to get a proper diagnosis by your dealership. This may be something that could be covered under warranty if found to be a defect. Please let me know if you have any additional questions.

Brandon
Chevrolet Customer Service

Thanks Brandon. With all the hot weather we are having now, i'll try to let the dealer take a look and see/hear.

[RayYork]

Originally Posted by Chevrolet Customer Svc

Please let us know how everything has gone for you at the dealership. We hope everything works out for you. We are also here if you have any questions at all!

Brandon
Chevrolet Customer Service

I took my car to my local dealership (Blade Chevrolet in Mount Vernon WA) yesterday and the tech's report is that it is functioning within normal parameters.

I gave the service writer a heads up to what has happened to this point (I copied and pasted my original post in an email to him).

They knew that they would likely not be able to replicate the issue.

The computer gave no codes and the system was operating properly.

I can't imagine that it is normal to feel the AC come on and leach so much power but this is the first manual transmission car that I have had with AC so it is possible that I am not used to the feel of the AC affecting the power as directly as it may not be in an auto. My gut feeling is that auto's hide a lot of the feedback from the power train that manuals transfer back to the driver. I'm likely just trying to come up with something that makes me feel better about it but that's the story I'm telling myself.

I agree that it was likely a frozen line or too high pressure that shut my system down in the desert and that's why it worked fine the next day.

At this point, the system is checking out fine and Chevrolet has it on record that there was an issue (perceived or actual) in the eventuality that it dies down the road.