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05 STS AWD 1SG
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Discussion Starter #1
Hello, I have a question:

1. I noticed yesterday (it's HOT here in Indiana) that the PASSENGER side AC is ice cold, and the DRIVER side is NOT cooling at ALL. I'm NOT using the passenger side temperature adjustment, only the normal driver side control. Can someone help me with this? Are there TWO different places to add refrigerant? Or, are there TWO compressors? Because the passenger side is COLD. It's the driver's
two vents that are blowing just fan air.
 

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05 STS AWD 1SG
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489 Posts
Discussion Starter #3
You probably just need to top off your freon, but check DTCs for a possible air mix problem.
Thanks Greg! But I'm sorry that I've only owned this car for a couple of months. What are DTC's? I'm not using the passenger temp setting at all, and just using the "Auto" mode all the time.

Thanks for your response! You guys are awesome!
 

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05 STS AWD 1SG
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Discussion Starter #5
Thanks. I just stumbled onto another thread where the person has the EXACT problem. He was more informative though. But it's EXACTLY my problem! I'll go by CAR-X and let them look at it on Monday I guess.
 

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05 STS AWD 1SG
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Discussion Starter #6
DTC = Diagnostic Trouble Codes. See the sticky at the top of the page.
OK, went out in the HOT weather and got my codes.

NO current codes, but here's what I have that were all followed by "history".

B1652 - Loss of Keep Alive Memory (KAM)
B1983 - Device Power Circuit Low
B1344 - HeaterDefrost/AC Door Movement Fault
U1064 - Loss of Communications with DIM

Doesn't seem like this is indicative to my current situation. There were a LOT of test areas, but they all said NO prior to their symbols as it toggled through.

Suggestions from here?
 

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2000 Deville, 1999 STS
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115 Posts
Hello. I had the exact same problem, cold passenger side but warm driver side. At first I thought it was an air mix problem because I obviously had cold air. But I didn't have any DTCs indicating a mix door problem. Then I read a few posts saying how this is a common problem when the refrigerant is low. I thought it sounded too simple. But I bought some refrigerant and.... THAT WAS IT!!! :) I now have ICEEE cold air on both sides!

Good luck!
 

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05 STS AWD 1SG
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Discussion Starter #9
Hello. I had the exact same problem, cold passenger side but warm driver side. At first I thought it was an air mix problem because I obviously had cold air. But I didn't have any DTCs indicating a mix door problem. Then I read a few posts saying how this is a common problem when the refrigerant is low. I thought it sounded too simple. But I bought some refrigerant and.... THAT WAS IT!!! :) I now have ICEEE cold air on both sides!

Good luck!
Thanks so much for the information. Since I'm a noob at this, I guess I'll take it to CAR-X and have them do a leak test and add refrigerant. Wish I could do it myself, I'm sure it would be cheaper... But I don't have very many tools.
 

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1997 SLS
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550 Posts
I'm a bit concerned about this code: B1344 - HeaterDefrost/AC Door Movement Fault. If it's history, clear the code and make sure it doesn't recur.
I know in the 98s and up, all the movement doors are electric. On my 97, the heater /defrost/ AC doors are vacuum activated. That said, it still sounds like you're a bit low on freon. There are simple kits available at automotive stores and for that matter, Walmart. If you try it yourself, do not purchase any freon product with a sealer in it! It will eventually ruin the system. If your leak is minor and a recharging doesn't get rid of your symptoms, there is one more thing you can try. If you know your system hasn't been maintained in many years, you can get a small (2 oz) PAG oil charge can and add that. I have a friend with an old 95 Lumina sedan and we added a can to his A/C, and so far, it's been working great. This would tend to re-moisten seals that could be leaking just a bit. If you have a serious leak, you will have to consider adding freon with a dye to detect the leak.
 

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05 STS AWD 1SG
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Discussion Starter #11
If you know your system hasn't been maintained in many years, you can get a small (2 oz) PAG oil charge can and add that. I have a friend with an old 95 Lumina sedan and we added a can to his A/C, and so far, it's been working great. This would tend to re-moisten seals that could be leaking just a bit.
Thanks. Would this PAG oil charge be added to an already full freon capacity? Or... would I add this at another place on the car?
 

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1997 SLS
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Only add the PAG oil if you are consistently loosing your freon charge thus getting the "low A/C refrigerant" message on the dash. Yes, it is added the same way as a can of r134a freon...thru the fill port on the low side, but if your current freon charge is holding, don't add it. This also assumes no maintenance that you know of or have records of, has been done to the system for many years.
 

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Discussion Starter #13
Only add the PAG oil if you are consistently loosing your freon charge thus getting the "low A/C refrigerant" message on the dash.
I've never gotten that message on the dash. Would that indicate that there's something else wrong with the A/C system? I have no dash messages....
 

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1997 SLS
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If you never got the "Low A/C refrigerant" message and you still get cold air on the passenger's side, it sounds like all you need is a top off on freon. You could do this yourself by getting a can of freon and a basic fill tube connector from say Walmart or an automotive store. Since your compressor is running, you can add some freon to see if the driver's side eventually cools off too. Or if you prefer to go to Car-X, they will probably try the same thing.
 

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2000 Deville, 1999 STS
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greg-sls is right. I never had any error messages about low freon. That's why I didn't give it much credit at first... until I came to the forums :)

I keep reading how this was a common and well documented symptom of low freon on a dual climate control system. Just not low enough to trigger a message or any DTCs.
 

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2003 Cadillac SLS 4.6L
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16 Posts
I'm the guy who had the other more descriptive thread.

It really sounds based on this like I need more freon. But we just checked the pressure and it seems to be good. 120 on the blue gauge, 100 on the red one. At the shop they're saying 120/100 should mean you're full.

I do not get the "B1344 - HeaterDefrost/AC Door Movement Fault" code, or anything like it.

But then I also didn't get a "low refrigerant" message when it was low.

So my A/C canister says to put 2.2 lbs in, but I have no idea how that translates into PSI. What should the PSI be?

I'm thinking of getting that kit to add freon but if I'm topped right up I'd rather not bother with that. It's just that I'd like to completely eliminate this as a problem before moving onto in-dash components that never had anything wrong with them before.
 

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2010 DTS
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Pressures will vary with temperature, but a ball park figure is about 27 psi on the low (blue) side and about 2.2 - 2.5 times the ambient temperature on the high (red) side. Update your profile to show your year and model so we know what we are talking about. I'm assuming it is an R134a system. If you have 120 on the low side and 100 on the high side, something is wrong.
 

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2003 Cadillac SLS 4.6L
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I read a lot of that guide. I am not sure of one important detail - I need to know what pressure zone I am in. To know this for sure, I need to know what the low side pressure is. Do I take this reading when the car is off, or when it stabilizes while running?

In any case, I think I have been successful. I bought a kit to recharge, fiddled with it all night the other night, then when taking the "defective" can back to the store, fiddled with the tap and realized that it did indeed work. Then I also realized that I could only charge when the car was running since the pressure was low. It's hard to say for sure what the pressure is when running, since it jumps around, but it appears to stabilize around 45 psi. When the car is off the pressure on the low side is about 114 psi. It started at 90. (it was 100 at my mechanic as previously mentioned, but I accidentally evacuated some when hooking this kit up for the first time)

It's a cooler day than my initial test, but I am pleased to say I'm getting 39 degree air on the passenger side (14 better than last test) and 46 degree air on the driver's side (47 degrees warmer than before) - the difference between the two has gone from 40 degrees to 7. I think the fact that it's a 66 degree night helps a bit, but either way, the two are much closer.

This is a major success! However, I'd be even happier if the two were equal or only off by 1-2 degrees.

So my only concerns now are, can my car take even morerefrigerant? Going from 90 to 114 psi with the system off, gave me a huge improvement. Can I put in more, perhaps up to 125 psi? Or on the other hand, did I already overcharge and put my system in danger? I'm thinking I didn't because this fix clearly worked so the car must be "meant" to have that much refrigerant, but who knows.

Some concrete specs about what the psi on the low side should read with the car off, would really hit the spot right now.

Here are the contents of my original thread: (this may as well be in one place to serve as a good reference for posterity)

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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