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2003 Cadillac SLS 4.6L
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16 Posts
Discussion Starter #1
I have a 2003 SLS. A/C Hose leaked over the winter. Needed a new hose and a recharge. Got the car back from the mechanic yesterday. the car blows cold air on the passenger side, and hot air on the driver's side. I can't figure out why.

My mechanic says that there is some sort of motor in the dash that directs the flow of air and it is not making the cold air come out that side. That makes sense. But I fear the problem is greater than that. Here's why:

I ran some tests on the temperature of the air coming out of the vents using a meat thermometer. First, with the A/C off and temperature set to the minimum, in other words, make it as cold as you can in here without R410A. I got 102 degree air coming out of the driver's side and 98 out the passenger side. More or less the same.

Then I switched to maximum heat with the A/C off. I got 153 out the passenger side, and 156 out the driver side. Basically the same again, but the driver's side tends to be a bit hotter. No big deal, though. so far.

I turn the A/C on and tell it to make me as cold as possible, fan speed on high, all air coming out the front. All four vents open. I get a cool 53 degrees from the passenger side but 93 from the driver's side - just 9 degrees better than with the A/C turned off.

So right away you must be thinking something is stopping the cold air from getting over to those two driver's side vents. BUT, if I close one of those vents, that nice cold air coming from the passenger side becomes 55 degrees. So some of that uncooled air made it over there. Close the other driver's side vent so that only the passenger side vents are open, and it blows 64 degree air.

So this cold air, and uncooled air are being mixed. The two systems aren't acting as though they are separate, and I thought they were, but I guess that's another story. So why is air getting into the system and not being cooled, and why only half of it? I'm telling it "send me cool air" and it's saying "ok, here's some cool air and some air that's not". And when I close those vents and say "I don't want that warm air" it's saying "too bad, i'll just mix it in with the cold air on this side" - So clearly it "means" to give me this warm air one way or another. I can't block it out or fool it. the system should be full of cold air if my AC is working from a mechanical standpoint, which it appears to be. So why is it half full of warm air?

I've never had a car with climate control before. Are there two compressors? Two condensers? Two rads? Perhaps both needed recharging and only one was. My mechanic says no, it's one A/C system only, and there's something in the dash probably wrong. I'm concerned because it never did this before, he worked on my A/C and now it does this. It's most likely due to his work so I have trouble believing the problem is within the dash. What could the issue be?
 

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2005 Deville Base, 2004 Escalade AWD
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275 Posts
There's just one set of hardware under the hood - one compressor, condenser, etc. The vehicle uses mix doors with electronically controlled actuator arms to direct airflow to passenger and driver. I believe there are two of these in your vehicle - do a search here, or better yet open Google in an Internet browser and in the search box type site:cadillacforums.com XXXXX where XXXXX is your search terms, e.g. site:cadillacforums.com seville air mix door. Was it like this immediately after leaving your mechanic or was the air cold on the driver's side for a while? Usually when the air is colder on one side or the other a top off of refrigerant is needed so I'm wondering if another leak has gone undetected or your mechanic did not use the recommended 2lbs (at least it is on my 2000) of refrigerant. I'd take it back to the mechanic.
 

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04 Deville, 11 DTS Premium, 00 Deville (sold), 02 Deville (sold)
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2,688 Posts
Your low on freon... it's one of the well documented quirks of the split zone A/C system in your Caddy. When the freon is low the drivers side A/C blows warmer than the passengers side.
 

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Super Moderator
2010 DTS
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87,573 Posts
First pull the DTC's. If there is an actuator problem, it should set a DTC. If not, I'd take it back again and have him check it out. You may have another leak and as mentioned, be low on refrigerant.
 

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1997 SLS
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550 Posts
Check your DTCs and see if you get a B0409, B0423, B1340 or B1341 code thru the ACM. There are other possibilities if it is the air mix system, but 00 Deville is right...typically your symptom is low freon.
 

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1999 Eldorado
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17 Posts
How about the opposite set of conditions? I have cool air on the drivers side and hot air on the passengers side regardless of what I do with the controls. I removed the glovebox compartment and took a look at the vacuum lines, they were intact but the actuator arm which controls the vents didnt move whatsoever when I took the temperature to its min and max in both zones. Would it be fairly safe to say it is the actuator? I had a recharge done recently as well.
Thanks
 

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Super Moderator
2010 DTS
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87,573 Posts
Yup. Sounds like your problem is that actuator. Disconnect it and move the door linkage by hand. Does that make a difference?
 

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Registered
1999 Eldorado
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17 Posts
yep, when I move the air mixer door by hand everything is ok. It's funny I don't get a code for it though. Ill see what the FSM has to say. For now I just have the mixer door set to let cold air through. Thanks.
 
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