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No A/C

Posted by alanrw 
June 29, 2012 01:27PM
Got into my baby and hit the A/C button. No joy. Is it the case that the clutch will not engage if the freon charge is below a certain pressure? Not sure if I have an electrical, mechanical or freon leak issue.

Diagnostic pointers?

And isn't it the case, when the a/c is switched on the electric fan should fire?

If indeed I am leaking freon, has anyone seen an overhaul kit for the E30 compressor?

thanks guys

alan



Edited 1 time(s). Last edit at 06/29/2012 01:31PM by alanrw.
rkj
June 29, 2012 05:16PM
Quote
alanrw
Got into my baby and hit the A/C button. No joy. Is it the case that the clutch will not engage if the freon charge is below a certain pressure? Not sure if I have an electrical, mechanical or freon leak issue.

Diagnostic pointers?

And isn't it the case, when the a/c is switched on the electric fan should fire?

If indeed I am leaking freon, has anyone seen an overhaul kit for the E30 compressor?

thanks guys

alan

Hey Alan

Did this happen abruptly; it was working fine then one day you came out to no ac?

Some older cars have a diode at the compressor line wire right before it goes in. The Bentley shows it plain. It's been my experience that the compressors just get replaced along with some of the lines and a few other parts for the change-over.

On my 88 the ac always worked well, but the last two years it has petered out and now it blows warm. I'm thinking of buying some freon from ebay and trying it out. Could be a cheap fix.

Regards, Rick
July 01, 2012 07:00PM
Yes, the electric fan should come on on the low speed setting when you turn on the AC. It should come on as soon as you push the AC button with the ignition switch on. The engine doesn't have to be running.

Yes, there is a low pressure cut-off switch. If the system charge is low, the clutch on the compressor won't engage. That doesn't affect the fan. That should come on no matter what.

Just because the freon (or R-134a if already converted) is gone doesn't mean it needs a compressor repair. You aren't likely to find a rebuild kit, but you can get a rebuilt one for big bucks. I'd be surprised if there was a problem with the compressor. Of course, I've been surprised a few times.

The AC system has about 11 o-rings in it and some of them are hard to find. There's one under a cover on the end of the expansion valve and four on the lines where they connect to the valve. The rest are at connections in the hoses, at the comressor, and at the condensor.

I converted my car to R-134a several years ago. I replaced all the o-rings, the two rubber hoses at the compressor, and the dryer. My compressor had been open to the atmosphere for so long it was dry inside, so I didn't have to change the oil. If that didn't kill it I would have to say they're pretty hard to kill. Once I got the o-rings changed, I poured in the right amount of oil, pulled a vacuum, and charged it up. After I lost a couple of charges through that o-ring I hadn't found yet on the end of the expantion valve I finally got it working. It's been good ever since, with some minor leakage requiring a little R-134a to be added every couple of years - no big deal. If yours hasn't been converted, you can get the parts you need at ACKits.com, and get the hoses made at your local industrial hose shop. You can change the oil in your compressor by removing it and just pouring the old stuff out. You can rent a vacuum pump from an auto patrs store, or take it to an AC shop and pay them to vacuum and charge it, if it holds a vacuum, after you get the parts in. If it doesn't hold a vacuum you'll have to check all the connections, but they might be able to pinpoint the leak for you.

John
July 01, 2012 07:15PM
One more thing I meant to mention: If your car hasn't been converted to R-134a yet and you decide to do it, don't put the adapter for the high side fitting on the R-12 fitting by the hood hinge. The adapter will stick out and interfere with the hinge. Use the high side fitting on the dryer instead. I was lucky enough to see this mistake on a car before I did mine, so I didn't have to learn it the hard way.

John
rkj
July 01, 2012 11:01PM
Quote
John Yust
One more thing I meant to mention: If your car hasn't been converted to R-134a yet and you decide to do it, don't put the adapter for the high side fitting on the R-12 fitting by the hood hinge. The adapter will stick out and interfere with the hinge. Use the high side fitting on the dryer instead. I was lucky enough to see this mistake on a car before I did mine, so I didn't have to learn it the hard way.

John

Hey John

Sounds like you were lucky, I've seen a few horror stories with the up-graded 134 conversions.

Rick
July 05, 2012 06:30PM
Why do the hoses and o-rings have to be replaced? Are they a different material for R12 compared to R134?

What is the methodology for finding a leak in an A/C system? Just a tool that is used to sniff around and locate the leak?

alan
July 05, 2012 10:08PM
Yes, the o-rings are a different material. The leak detector can be a propane torch with an asperator to suck up the freon and run it through the flame and it turns green.

Bob in Everett
July 06, 2012 11:30AM
Is the expansion valve right by the acumulator which is right behind the passenger headlight?

alan
July 06, 2012 12:13PM
Quote
alanrw
Is the expansion valve right by the acumulator which is right behind the passenger headlight?

alan

No, unfortunately it's under the dash right beside the evaporator. You get to it by removing all the stuff beside the glove box (on LHD cars). It's not too bad to get to, but it is crammed in there where it's hard to get a wrench on the fittings. They're nice and big too, so you have to use big wrenches, and the best position to be in to get any torque on the wrench will mean you have to be twisted up like a pretzel. In other words - typical under dash work. At least the o-ring at the end of the valve can be done once you have removed the valve.

On the hoses and o-rings, I didn't mean to go silent, but I got cut off from the internet by storms in the area for a few hours. Bob's right, different materials. The R-12 rings are buna (the usual material if you just buy o-rings at the parts store) and the R-134a rings are neoprene, which they color green so you can easily see that they're for R-134a. You can get black neoprene o-rings too, but the ones at auto parts stores are usually green. I've heard the hoses for R-134a have a liner that's supposed to keep the refrigerant from seeping through the rubber although I don't know that for a fact. I do know that my new hoses had R-134a printed on them, so there might be a difference. I bought new hoses because my old ones were crappy replacements that had the ends held in by hose clamps. Total junk and unsuitable for the kind of pressure you find in an AC system. The ends have to be crimped into the hose or they'll leak. Good original hoses might be OK to re-use.

There might also be a difference in the expansion valve. I bought a replacement, but couldn't install it because the threads weren't right. ACKits didn't have anything else for my car, so I just reused the old one. It seems to work fine.

I found my leaks by using green dye in the refrigerant charge. It was pretty easy to spot. Green dye was all over the valve.

John
July 06, 2012 03:06PM
Thanks for the input John. I think I can get new hoses made up here. I don't think BMW has anything left for the E30. I will have to do an internet search. Is it not the case that the only hoses are at the compressor and everything else is hard tube lines?

alan
July 06, 2012 06:46PM
Quote
alanrw
Thanks for the input John. I think I can get new hoses made up here. I don't think BMW has anything left for the E30. I will have to do an internet search. Is it not the case that the only hoses are at the compressor and everything else is hard tube lines?

alan

Bavarian Autosport had the hoses back when I did mine (8 years ago) for about $75.00 each, but the ones I got made at the hose shop were half that price. Now that you ask, and make me think about it, there is another rubber hose. The low pressure line back from the evaporator to the compressor has a rubber section. That could be where I'm losing a little charge over time. I don't have any places where there's green dye visible, so maybe it's making it's way through the hose. In any case, I'm not going to open the system up to change that hose. 8^)

I just checked. Bav Auto has the Comp > Cond hose for $65.00. Not too bad if you can't find a shop to make them.

John
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