Air Conditioning Problems/B4

Hello all..... I'm hoping some one out there will be able to steer me in the right direction. The A/C in the car quit working about 2 weeks ago. The compressor still comes on when the switch is pushed but the air is not as cold. It is just barely noticeable that it is working at any blower speed. The compressor does not kick on and off as if something is wrong. It runs constantly and smoothly as if everything is ok? /images/graemlins/confused.gif

I just got back from the dealership. $89.00 to diagnose the problem! And they say that the following components need replacing: Compressor, Dryer, Expansion valve and evaporator. It sounds to me as if they are just going to replace everything and do some parts swapping instead of doing some real troubleshooting to replace a bad component. All for the bargain price of $1425.00?? /images/graemlins/eek.gif You have got to be kidding me. /images/graemlins/rolleyes.gif I would assume sell the car before I pay that. /images/graemlins/mad.gif

Any help greatly appreciated.......

AJ
96 Passat TDI

I think the question is where is it leaking from?

Any part replacement will result in changing the dryer.

http://forums.tdiclub.com/showflat.php?C...h=true#Post9589

Don't know if your symptoms are different, but my problem is fixed.

Jerry

Weedeater,

If it were leaking wouldnt the compressor be shutting off because of some kind of pressure differential? All of my previous expierences with leaking systems is that the compressor will not kick on at all or it will kick on and off constantly (with a leak)......

AJ
96 Passat TDI

Jerry,

My problem sounds exactly like yours.... Was your low pressure hose getting cold after it quit working? Mine is warm. And yes, it blows cool. Just barely cooler than the outside air temp. Without recirculate.

I havent had the 134 removed. Is that a good place to start? Do you think it would be a good idea to got ahead and replace the drier and expansion valve only and work from there? Or could these components possibly be ruined by something wrong somewhere else?

Great link...... Thanks....


AJ
96 Passat TDI (Hot and Muggy in Florida)

Where exactly is the expansion valve ona B4? Is the drier below the air box?

AJ
96 Passat TDI

The expansion valve is on the firewall...just follow the lines where they go into the firewall, and you see a little aluminum block (some cars have a little expansion valve "cozy" over them).

I am drawing a blank on where the drier is, but I thought it was under the right front corner somewhere, like behind the bumper skin.

As far as diagnosis is concerned, you would need to see what the pressures are while the compressor kicks on. Since it does come on, that would lead me to believe the charge of refrigerant is okay, or at least enough to keep the low-side pressure switch from opening.

These are "variable displacement" type compressors, and when they fail it is usually the swashplate deal inside the unit...which means replace the whole thing. It is a good idea to replace the drier when any compressor work is done, because if there was any shrapnel blown into the system chances are it will end up in the drier. Some can also get into the expansion valve, but not as likely, as that is after the drier and condenser. You'll need to blow out the condenser really good, too. Evaporator core should be fine.

Incidentally, if the dealer quoted you 1400 bucks for a new compressor, drier, evap, expansion valve, that is a bargain! I wouldn't do it that cheap!

I just installed a new compressor in my 1991 Jetta. The cost of that was almost $300, plus $80 for a new R134a expansion valve, $45 for the drier, and my condenser was pretty messed up from 300k+ miles of bugs and rocks...so I replaced that for $320. Not to mention all my labor was mine, plus refrigerant. And the whole entire dash needs to come out of the car to do an evap, so I dunno how they came up with that price. I would think closer to 2 grand for all that at a dealership using VW parts!

Thanks oilhammer. I wanted to try the old light tap on the expansion valve. I was pretty sure thats where it was. I was not positive though. It is covered in some black plastic.

So your saying the compressor could still run even if something inside of it blew apart?

I'm trying to find a starting point and get some real input from people who have been through all of this before I go out and start having other people test it. Would knowing the pressures be of any help in determining if the compressor is bad or not? I have a friend who knows a little about A/C and has the gauges to check 134 systems.

I really appreciate all the help!! November in Florida is just like July........ HOT and HUMID!

Thanks,

AJ
96 Passat TDI

I am experiencing the exact problem with my 97 B4. I was told by an independent mechanic to replace the same. I don't have a written quiote but I plant to have it fixed come next month.

If you are in a hurry to get yours fixed, I would be glad to hear how you solve it.

pinehead,
The low pressure hose that is supposed to be cold was warm and the high pressure hose was cold. From what I gather, the opposite of what they should be. My theory is that when the shops removed and reinstalled the freon in my system, trash that was blocking the orifice within the dryer (drier) would come loose and everything would then be fine for a couple of days until the line would clog again. The expansion valve is $48.78 and the drier is 89.00 for my car from www.vwparts.com . I would recommend getting both since if you only replace one of them, it could be the other one that was bad and you would have to pay twice for labor. Good luck!

Jerry

P.S. I would also order a couple of each of the o-rings for each part.

OH is right. If the compressor is coming on, that indicates that there is sufficient charge in the system for activation. If it had completely leaked out, the compressor would not come on.

As for the compressor cycling, this is a variable displacement unit. It won't do that. Well, at least not like older models.

Determining the pressures will help to see what the compressor is doing.

These expansion valves seem to be flakey. Normally you would expect the 'valve' to simply be an orifice between high and low pressure. Something with no moving parts. But either they are getting stopped up or otherwise plugged on some cars and replacement seems to take care of the issues.

I had a similar problem, and it turned out all that was wrong was that the fan up front by the dryer had been unplugged by the Majestic Automotive mechanic.

Unplugged or failed, this (lack of fan) air circulation caused the system to overheat and purge the R134. Check to make sure this fan is working before delving into the big cost items.

Total cost was around $100 to diagnose and recharge.

Pine, if you have someone with access to R134a gauges, check the pressures first.

As a rule of thumb, with the A/C off the low and high side will be the same (static)...usually around 50 to 80 psi, depending on the temperature.

When you turn the A/C on, the high side will shoot up, and the low side will shoot down. There are a wide range of variables (temperature, RPM, radiator fan efficency, etc.) but generally your high side will go over 200 and the low side will go down to around 40ish. The change from static, however, should be pretty quick. If your friend has gauges, he/she will more than likely know if the compressor is working.

The expansion valve has a little tiny moving part inside, that will vary the opening a bit depending on the pressures...this is to get the evaporator as cold as possible without letting it freeze up. Older American cars use oriface tube systems..different animal. If that valve is sticking, it won't allow a difference in pressure, and that difference (pressure drop) is where the cold air comes from.

Mine stopped working two years ago.

The condenser was leaking, which is the most common fault.

I paid someone to put dye in the system and that is how we found the leak.

It cost me £120 GBP for a new one, which I fitted myself, and I got the company aircon technician to refill it for me.

Two year on it is still working well.

I just had the same problem. I bought a recharge kit from a local auto parts store for $19.99 ( the one with the pressure gauge).. 1 can of 134a brought the low side pressure up to 45psi and the air was cold again.. total time spent 20 minutes ( because I read the instructions on the package.) it will take 5 minutes next time.. If there is a leak it seems to be a slow one..

I have a friend who is a service manager at a Mercedes dealership. He said they test with a dyed refrigerant. Because most of the time leakage is the problem and this defines where exactly.