AC Problem - Need Help

89BMWE30 · 06-03-2008, 01:26 PM

I have a problem with the air conditioning on my 89 E30 that I could use some help on. The A/C blows cold (not really cold) when the car is in motion but if I am stuck at a red light, it starts to get warmer. I had a hose replaced last year and it has worked alright since then but now since it is summer I can really feel how its working or not working. I don't know what to check or replace and I don't want to take it back to the shop not knowing what might be wrong with it. I was hoping that someone might be able to give me a hint on why this happens.

Jeron · Jeron's Garage

My guess would be low freon. Does your front fan come on with the AC?

Yurick · 06-03-2008, 04:59 PM

It sounds like it's low on freon. I've got the same issue on my '90 convertible.

89BMWE30 · 06-03-2008, 06:48 PM

I checked the front fan - its working fine . I checked the compressor and the pulley on it spinning fine. The A/C seems to be blowing semi cold right now but it also around 78 degrees outside and I usually drive when its around 98 degrees outside. I thought it might be freon as well but I can't find R12 at the auto parts store. I have heard that "Freeze 12", which is a substitute for R12, would work well as a replacement. Has anyone heard about this product?

coolbear1 · 08:30 PM

Check the sight glass on top of the reciever dryer. See if youy can see any bubles when the car is at idle. It is located behind the driver side head ligt. THe sight glass is on top.
Clean it good and use a flashlight. It should be totaly clear. check it idling and at about 2000 rpms.
If you can see the freon moving through it, it indicates low charge.

Your not going to find R12 anymore, and if you did it is illegal to sell it to you unless you have a licence.
What did they use when they replaced the hose?
I'll bet it wasn't R12.
I do A/C work for a living and am licenced and I can't find R12 anymore.

89BMWE30 · 06-04-2008, 07:29 AM

Thanks - I'll check the sight glass. I don't know what they used instead of R12.

automech · 06-04-2008, 11:12 PM

If the system has over 45psi, then the cycling switch should close and send power to the compressor. Check the cycling switch with a test light, there should be power on both sides. If so, then check the a/c clutch itself. Too low on the low side could be low on freon. Just need more to go on to properly diagnose this concern.

Manolito · 06-05-2008, 05:54 AM

I was going to vote for a problem with the electric fan in front of the radiator, since the freon circuit does not know whether you are moving or not, so a weak A/C due to low freon should not change much when the car is moving.

Since you say that the fan is working fine, I would look for blockage (bugs, pet hair, leaves) in the center area of the radiator. Try to spray the garden hose outward from the engine compartment and see what you can flush out.

I don't think you can mix Freeze 12 with R-12.

As someone noted, it is possible, but unlikely, that they used R-12 after the last repair. If they converted the system to 134a, they should have changed the fittings. Look on the Web to see what R-12 vs 134a fittings look like.

I have a 30 lb cyl with 20 lbs of virgin R-12 here in Sacramento, but that is no help to you if you are anywhere else in the world. Your location?

coolbear1 · 06-05-2008, 10:10 PM

You can determine what kind of refrigerant is in anything.
Use an accurate gauge and a temperature/pressure chart. The The differance in relationship is small in the case of 134A verses R-12, but it is there, and is, 100% reliable.