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VW GTI no cooling Hi and Low the same pressure?

magnetchief on Tue April 29, 2008 10:21 AM User is offline

Year: 1998
Make: VW
Model: GTI VR6
Engine Size: 2.8
Refrigerant Type: R134a
Ambient Temp: 90
Pressure Low: 35
Pressure High: 35
Country of Origin: United States

Hi guys, glad I found this forum.
Maybe someone could advise me.
I recently purchased a GTI, nice car but the AC does not work.
I have 'some' AC experience, mainly from industrial marine (Navy) units so I thought I might try to fix the GTIs ac.

Anyway, where to start.
There is absolutely no cool air from the vents. Dial temp shows 85 deg. (approx ambient)
Ac is on full, ac clutch is engaged.
Pressure readings on the low and high side both read 30 -35 psi. Now even I know this can't be right.

With the engine off, pressure readings are 90 psi for both high and low.

Am I looking at a new ac compressor?
If so, what else would I need to replace?
I am assuming the dryer and expansion valve too.

Thanks in advance for any help.
Steve


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Once Navy alway Navy

mk378 on Tue April 29, 2008 10:54 AM User is offline

This is not right. Do you have the valve wheels on your manifold closed (they need to be closed to measure pressures properly).

I think your car will have a variable displacement compressor, but if engaging the compressor makes a difference in system pressure it is not completely dead.

TRB on Tue April 29, 2008 10:55 AM User is offlineView users profile

If the clutch is engaged and you have a good static pressure. You may consider checking/replacing the control valve in the compressor. Not as simple as some of the GM control valve replacements. I would suggest the drier be replaced and if you can blow through he valve it should be fine. Proper flushing to remove the oil would also be suggested. Check out Karl's flush procedure in the tips forum of this site.

1998 VW Golf GTI listing.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

Chick on Tue April 29, 2008 4:31 PM User is offlineView users profile

Like Tim said, if the static pressures are good, it may be the control valve, but my guess is it's just about empty. I would recover, then recharge the exact amount back into the vacuum. Pressures should fall in line, if not, I would change the compressor (if they are more or less even) The control valvews in those are not as easy as GM control valves....Just my opinion... hope this helps..
Check out Ackits.com for "qualuity" and resonable parts..You can't go wrong...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

TRB on Tue April 29, 2008 10:52 PM User is offlineView users profile

Quote
Originally posted by: Chick
Like Tim said, if the static pressures are good, it may be the control valve, but my guess is it's just about empty. I would recover, then recharge the exact amount back into the vacuum. Pressures should fall in line, if not, I would change the compressor (if they are more or less even) The control valvews in those are not as easy as GM control valves....Just my opinion... hope this helps..

Check out Ackits.com for "qualuity" and resonable parts..You can't go wrong...

Agreed, 35PSI across the broad could very well be a leak.



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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

badufay on Tue April 29, 2008 11:12 PM User is offline

Hey guys...greetings from Iraq (Ice, I will get you those pics of our systems as soon as the dust goes away). As most of the guys on this board can attest, i have gained too much experience on these vw compressors the last year. The RCV that they are talking about does go bad on these compressors, and yes you have to pull the compressor and pull the head off to change it, and no, don't try and remove it by placing a bolt in there either Like they said, before you start tearing things apart and replacing expensive components, evac, vacuum, and charge with straight r-134a (with some UV dye maybe if you have a leak). See where this puts your pressures, and not to insult your intelligence, but do like they say and double check your knobs are closed on the gauges. Since your low is going down into the 30 psi range, the compressor is sucking, and if the RCV is malfunctioning, your not going to get a high side pressure (someone please correct me if I'm wrong on that, thats just been my experience on these vw's). Oh, and if you need to get a new compressor, buy from these guys (new or reman), don't screw around with the autozone ones, you'll end up changing it again in a week, and then again a few months later, they are just not good quality (thats based on my experience). Good luck with it, and keep in mind, these vw's are VERY sensitive to the amount of refrigerant in them, don't over charge it, or under charge it. throw a thermometer in the vent and see what your vent temps are when it is all said and done. Good luck,
Ben

magnetchief on Wed April 30, 2008 8:27 AM User is offline

Thanks for the advice guys.
Well I now have cold air
Not quite sure about the pressures mind you.
I was checking the various components of the ac system and noticed that there was a split / broken vacuum pipe under the fan control modal.
I could not figure out exactly where it went but it looked like it might hook up with the vacuum reservoir under the fender.
I repaired the pipe and low and behold my air vent temp started to drop like a rock (I use a dial temp probe poked in the vent Badufay)
I figuring that there must have been a vent / flap issue.

Back to the pressures. Yes both valves are shut.
The pressures still look wrong mind you. Now with the cold air I have 15 - 20 low and 50 high side.
I guess the best thing to do is evacuate, pump down and recharge.
I have a vacuum pump, gauge manifold , r134a hell I even have the nitrogen (I work in cryogenics and high vacuum research) but no way to evacuate the system.
Is this something I could get my local shop to do for me?
Would they even do it? I figure they would want to service the whole thing from start to finish.
What about the oil ?
This is the specs I have.

MKIII A/C Data Page;

System fill spec: 28 oz of R134a - 3.9 oz (total) of PAG based oil.

Typical pressures should be 205 Psi high side, 17 Psi low side.

When I evacuate the system am I removing the oil too?
Thanks for the advice guys, it makes a nice change to find knowledgeable people. As opposed to the idiots on vwvortex



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Once Navy alway Navy

mk378 on Wed April 30, 2008 10:05 AM User is offline

Pressure must be measuring wrong. You wouldn't get any cooling were the high side really 50.

Since you have cold air, it is safe to assume the refrigerant system is OK and leave it alone.

magnetchief on Wed April 30, 2008 11:22 AM User is offline

I'm inclined to agree.
"If it ain't broke don't fix it "

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Once Navy alway Navy

magnetchief on Fri May 30, 2008 2:30 PM User is offline

Well that didn't last too long

We had cold air for about a week then noticed that the engine was 'sagging' whilst driving along.
You could actually feel the car slowing then speeding up. The ac stopped cooling so we figured something had gone kaput.
When we turned off the air the car returned to normal speed.

Anyways, a week has passed the ac does nothing, you can hear the ac clutch kicking on but no cold air.
The expansion valve shows no cooling effect. pressures are 20 low and 50 high

This is after having evacuated with a vacuum pump. held the vacuum pretty well so I assume no leaks.
We charged with exactly 28 oz of R134a.
BUt no cooling effect at all when running.
Only cool spot is the bottom of the liquid receiver.

Are we now looking at a new compressor? If so I guess I may have to send someone some money



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Once Navy alway Navy

TRB on Fri May 30, 2008 2:55 PM User is offlineView users profile

Drier should not be cold with a TXV system. Anyone add a sealer to this vehicle? Current pressure readings would be helpful.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

magnetchief on Fri May 30, 2008 3:41 PM User is offline

Not that I know of, but have only had the car 6 months, previous owner was a bit of a 'cowboy' so who knows.
Pressures are 20 low and 50 high.

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Once Navy alway Navy

mk378 on Fri May 30, 2008 3:45 PM User is offline

There must be an obstruction somewhere between the compressor outlet and the high side service port where you are measuring the pressure. Like TRB said, nothing on the high side (such as the drier) should be cold.

magnetchief on Tue June 03, 2008 4:44 PM User is offline

Ok so rechecked everything. pressure when the compressor is engaged is 25 psi low and high side. Low side fluctuates between 20 and 25. whilst running.
Drier feels colder but not cold like ice, just colder.
Lines before the expansion valve feel hot.
No cooling at all.
Any advice appreciated, hoping to get this working somehow. It's Florida and getting warm


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Once Navy alway Navy

mk378 on Tue June 03, 2008 4:48 PM User is offline

And you still have much higher static pressure (equalized, after the compressor has been off for a long time)? Like 90-120 psi depending on the ambient temperature, on both sides.

Edited: Tue June 03, 2008 at 4:50 PM by mk378

magnetchief on Tue June 03, 2008 4:58 PM User is offline

Yep, low is almost off the scale and high is a corresponding value.
Not sure of the value exactly but I could check this evening.

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Once Navy alway Navy

Edited: Tue June 03, 2008 at 4:58 PM by magnetchief

mk378 on Tue June 03, 2008 8:02 PM User is offline

There must be a blockage between the compressor and the high side measuring port. Recover the refrigerant, take the system apart and try to blow air thru the various components. Beware that if there is sealer in there, it will start to harden when the system is opened. If the evaporator is one that is built into the dash and difficult to replace, be prepared to flush it immediately to put emphasis on trying to save it. Parts that contain hardened sealer cannot be re-used.

magnetchief on Wed June 04, 2008 3:57 PM User is offline

Damn, thanks.. That does not sound like good news.
Any ides as to what sort of chemicals I can use to flush?
Mind you I will try a search too


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Once Navy alway Navy

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