Can't figure out why I'm not getting cold air - compressor works and system is charged (I think).

[natesi]

Howdy all,

I just bought a used car (2007 Elantra) and can't figure out the AC problem.

When the AC is activated the AC compressor turns on -- as well as the condenser fan. Unfortunately, no cold air comes out of the vents though.

I planned on putting some dye and little refrigerant in the system to see where the leak is, and go from there. I got a gauge for the low-side as well as a can of r134 with dye.

However, when I connected the gauge, there appeared to be plenty of r134 in the system -- the gauge read 28psi when the ambient temperature was 52 degrees.

I didn't add any dye or refrigerant - left everything alone.

Soooo.... this is not what I was expecting. It appears I don't have a leak, right?

Where do I go from here though? The compressor is turning on, there's good pressure in the system (as far as I know), and no strange noises -- but I can't get any cold air out of the vents. So I'm confused.

I'm trying to get the AC squared away so I can use the defrost function this winter, without damaging the compressor, or harming the system at large. Plus, I live in the rainy PNW, so it's nice to get moisture out of the cabin and make sure everything is staying dry inside. However, from what I can tell, the AC isn't working and therefore isn't pulling any humidity out of the cabin.

Thanks,

-Nathan

[Cusser]

Disclaimer: I'm not an AC professional. But my advice is free, and worth every penny.

52F is pretty low temperature to try any AC diagnosis. But 28psi is pretty low.

I'd get a real service gauge kit if you want to continue diagnosing by yourself. And I'd run away from what you purchased if that can contains any sealer in addition to the R134a and UV dye, sealer chemicals can ruin a system big time !

Your system "could" be low due to a small leak over time, causing the low pressure switch to stay "open", but adding refrigerant yourself is a big guess. Correct way is for an expensive machine to pull out the refrigerant, then add the total/sticker amount BY WEIGHT.

[natesi]

Disclaimer: I'm not an AC professional. But my advice is free, and worth every penny.

52F is pretty low temperature to try any AC diagnosis. But 28psi is pretty low.

I'd get a real service gauge kit if you want to continue diagnosing by yourself. And I'd run away from what you purchased if that can contains any sealer in addition to the R134a and UV dye, sealer chemicals can ruin a system big time !

Your system "could" be low due to a small leak over time, causing the low pressure switch to stay "open", but adding refrigerant yourself is a big guess. Correct way is for an expensive machine to pull out the refrigerant, then add the total/sticker amount BY WEIGHT.

Thanks. No; I didn't add anything to the system. But the bottle I was going to use didn't have any sealant in it anyway -- I've heard that stuff is not good to add.

I figured for 52 degrees outside 28psi seemed OK -- but I'm a total rookie.

I think, at this point, I'll probably have to have a pro take a look at it. My goal was to diagnose it far enough, before going in, to make sure they were not going to bend me over.

QUESTION:
Do you all think I should WAIT for warmer weather before taking my car in to get looked at? I was reading in another post that you want the ambient temperature somewhere around 80 degrees F when doing AC work? We're lucky to break 50s here, now. Can a shop do good AC work in the late fall / winter? Or would it be an inferior repair?

Thanks,

[Cusser]

QUESTION:
Do you all think I should WAIT for warmer weather before taking my car in to get looked at?

Yes. You have some pressure/refrigerant in the system, so moisture air won't get in. It's easier to diagnose in warmer weather.

I figured for 52 degrees outside 28psi seemed OK -- but I'm a total rookie.

I think, at this point, I'll probably have to have a pro take a look at it.

Good plan.

[JohnHere]

If you had the professional equipment that you need for the job, you could start by having a pro shop recover the refrigerant that's in it now and repair the leak(s). Then, you could evacuate and recharge it to specs at home. But doing it that way would mean you would have to invest in the proper tools and virgin refrigerant.

If working outdoors, recharging the system in ambient temperatures like you're seeing at this time of year is possible but will result in a very slow rate-of-charge without warming the refrigerant container(s). Diagnosing a system at temperatures in the 50°F range is a "horse of a different color" entirely.

If you decide to tackle the job yourself, it would be best to wait until the ambient temperature reaches around 80°F or, if you want to fix it right away, have a pro shop handle everything as already mentioned.

[natesi]

Thanks. I just got the car back from the shop yesterday.

They pulled all the r134 out and said the system held a vacuum. They could not find any leaks.

However, the system only had .35lb of r134 in it and they said the spec is 1.16 lb.

They filled it back up with dye and said it passed a test charge -- and could NOT find any leaks. They said to run it like this and when it gets weak bring it back and they can find the leak.

All total the charge was $354. They said their work comes with a 1 year warranty and there will be no charge for labor if they have to repeat this (or something) -- I would just have to pay for the refrigerant. They said they didn't add any oil into the system, as in their experience, when they evacuate the system maybe only 1 drop of oil is lost.

If it ends up being the compressor that leaks they said plan to spend about $1500 ish to replace it and get the system going again -- assuming it doesn't send metal bits all throughout the system.

So, it's just a waiting game now -- see how long it takes to leak out.

As a side note: The compressor seems quieter now that it has more refrigerant. Do you think it was getting damaged by running it with such little refrigerant? I almost never ran it unless I had to clear off the front windshield. But when I test drove the car, the previous owners look like they kept it in "defrost" mode -- so it was probably running all the time.

Thanks,

[tbirdtbird]

"Do you think it was getting damaged by running it with such little refrigerant? "

The refrigerant carries the oil all through the system. Of course, only the comp needs any oil. So, yes a comp can be harmed by a charge level that is too low.
As you stated, only time will tell

[natesi]

They said they didn't add any oil back into the system though. I hope they didn't do things improperly.

[tbirdtbird]

From what you describe it sounds like they did OK.
Evacuation/recovery of refrigerant of a system with a pro machine seldom removes much oil at all.

Were you able to see any 'wet' areas on any fittings or hoses? Or areas where dirt had collected? (leaking oil tends to attract dirt)

[natesi]

I haven't seen anything like that.