My CTS has a bad AC problem when the temparature gets over about 90. It will not cool down in stop and go traffic. I drove for 15 to 20 minutes in stop and go and it NEVER cooled down. The air coming through the ducts was as hot as outside! As soon as I could cruise consistantly at or above 35mph it worked fine. Once you get back into stop and go it gets hot again though! They just called and said they couldnt duplicate it! WTF!!! It does it ALL the time when its over 90 (Its 98 here today)!! I told them to keep working on it. Any ideas??

My CTS has a bad AC problem when the temparature gets over about 90. It will not cool down in stop and go traffic. I drove for 15 to 20 minutes in stop and go and it NEVER cooled down. The air coming through the ducts was as hot as outside! As soon as I could cruise consistantly at or above 35mph it worked fine. Once you get back into stop and go it gets hot again though! They just called and said they couldnt duplicate it! WTF!!! It does it ALL the time when its over 90 (Its 98 here today)!! I told them to keep working on it. Any ideas??

98, boy I wish it was that cool here. Everyday for the last 3 weeks it's been btw: 110 & 117. The AC works fine at all speeds. Do you have the recycle button engaged, I forget to do that sometimes and it does make a difference.

The Compressor Clutch may not be engaging fully, but without seeing the car thats a guess at best.

Sounds like a fan problem or an airflow problem of some sort.
If there isn't air moving over the condensor the heat won't dissipate from the refrigerant and it won't cool.
If they are sure it's not low on charge, then they need to concentrate on the fan control system and make sure it's working.

Actually, it also may be overcharged. Sometimes the a/c won't work if there is too much freon in there. I don't believe it's a fan problem because your engine would overheat.

Check the fan operation... Sounds like the high speed or secondary fan isn't working... Engine will still cool if the primary or low speed fan is operating but it won't pull enough air to cool the condensor when the vehicle isn't moving or moving slow...

I just e-mailed the responses so far to my service guy- hopefully that helps! Thanks guys, keep em comin!

I can think of two things that will cause this. First the high pressure cut off switch may be failing. second is that if you always have it on max-a/c when it's humid out you can actually freeze the evaperator core in the dash, thus stopping the flow of air through it and only producing hot air, cold air will return after a short time where it will thaw out.
the dealer can try to reproduce this in the service bay by running your car with a cover over the front end ( no air flow ) obviously someone needs to watch the coolant temp. VERY closely.
Chris

You would think the dealer would check everything but if they are not driving it under the same conditions they are not likely to notice a problem.

I had a the A/C that would blow cold then blow hot on a 2001 GMC but it had nothing to do with city/hiway driving. It turned out the be the low pressure switch had corrosion on the terminals and it was a new vehicle at the time. Part was back ordered so they took one from new vehicle on the lot. I recall when I went in with it, it was working AOK so they said its ok. I disagreed and the service manager took a ride with me to explain how to operte the A/C (like I did not know) and it started to blow hot air and he said well that never did it for us before.

Ding Ding Ding!! My service guy just called me and said some 04s had a problem with some pressure switch thingy. They are having the part overnighted and will install it next week (I need the car for the weekend)! Betts Cadillac kicks ass! He didnt know for sure if this switch was the problem since they couldnt reproduce my problem but they are replacing it anyway. Ill let you guys know if it doesnt work. Thanks for all the great help as usual guys!

Ding Ding Ding!! My service guy just called me and said some 04s had a problem with some pressure switch thingy. They are having the part overnighted and will install it next week (I need the car for the weekend)! Betts Cadillac kicks ass! He didnt know for sure if this switch was the problem since they couldnt reproduce my problem but they are replacing it anyway. Ill let you guys know if it doesnt work. Thanks for all the great help as usual guys!
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I am having a similar problem, could you tell me if was the low pressure recycling swith or also known as the A/C compressor refrigerant low side switch.

Please help if you can. Thanks!

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I am having a similar problem, could you tell me if was the low pressure recycling swith or also known as the A/C compressor refrigerant low side switch.

Please help if you can. Thanks!


It was the high pressure switch or high speed switch. High _______ switch is what I remember my service guy saying. It did end up fixing th the problem!

Thank you!

Ahhhhh.....happy endings. :alchi:

Dear B Hoth,

From what you understand about the problem I am having, do you think I should replce the low pressure switch or the high pressure cut off switch?


I could sure use some good advice.


Thank You!