mx22

Well, it seems like I will have to handle this by myself in the end... Called the shop that did PPI for me and they said it will run me anywhere up to $2.5k to get it fixed (and more if it's a new compressor). I can always sink the money into the car, but why not to try to fix it myself? (last time I had ABS light on, they told me it was an expensive process to go through the system to find what is wrong; thanks for a tip from this forum, I replaced the relay and now it all works - cost me less then $30...)

When I bought the car in April 2010, air conditioner used to blow coldish air. Not super cold, but cold none the less. Within a month, the cold air was gone; it was pretty much blowing outside air and I simply stopped using it.

I assume there a leak somewhere in the system?

What should the first step be and what do I need to have on hand (tools & etc...)?

Thank You!

Speedtoys

Id guess...recharge it with dye, and find the leak...


I had one fitting that was just loose..same thing..cold..then warm later in the month.

SeanR

There are so many seals it is just best to jump in and start replacing them all. If you don't, you will just be changing one or two, filling up only to loose the freon a bit later. Only to repeat the process again.

Best to do them all.

tveltman

Strongly agree. Do all the seals, replace the expansion valve, and call Roger for the receiver/dryer that fits. I've not yet rebuilt an A/C compressor, but I have one sitting around that I've been meaning to play with. Also, make sure you remember the seals on the inlet/outlet of the compressor. They are relatively large o-rings if memory serves, and they are underneath the metal plate that screws onto the compressor. You might also consider taking the unit to a welder and having them weld the auxilliary schraeder valves closed (the compressor has a set on it that don't get used). Make sure you use the new o-rings that are compatible with r-134a and r-12, so that no matter which way you go, you will be set. They are green in color.

My other advice is to pressure test the system with nitrogen or argon, or if you don't have access to a tank, you can use an air compressor. Make sure you put an industrial grade water trap on it, and soak the thing in a bath of denatured alcohol and dry ice while you are running the compressor. You may have to fab up a manifold to hook your compressor to the car. I did, but it was 100% worthwhile. I was certain my system sealed under pressure. You will also need to beg, borrow, or steal (or buy, gasp!) a decent vacuum pump. Harbor freight has a nice one for like 150, and that thing pulls serious vacuum. The little venturi ones for an air compressor are garbage, don't bother trying. Vac overnight once the system is leak-tight and assembled, and then you can backfill refrigerant into the vacuum. I personally prefer r-12, if you can get it, but there are plenty of people who have had good results with r-134a. R-12 is more forgiving of moisture in the system though, and it works "better".

mx22

Thanks a lot for the suggestions, will change all of seals (I hope Roger carries those). Is there a write up on how to do this (preferably with pictures; you are talking to a newbie here

Thanks!

tveltman

Mmm, I think Wally Plumley may have written one for 928 specialists, although I'm not sure. I remember there being some instructions somewhere as to where all of the o-rings were, but I don't remember where. Also, if you don't want to fill the system yourself, you may be able to put the thing back together, leak check it, then vac it out and take it somewhere to have it filled.

ponenc

I know someone here has the special HVAC publication on PDF, which might be helpful. I could use it. I'll will be shadowing your progress I have the same issue with my S4.

Also check this out - write up by Dwayne H. I have used his tutorials on other repairs very helpful; picture intensive and newbee rated:


http://928oc.org/Heinsma_Dwayne/pdf/...ocedure_V2.pdf

good luck and keep us posted.

mx22

ponec,

Thanks, I know of Dwayne's write up. I hoped for some for newbies though lol, something with clear step by step instructions - start here, then there and etc... That's not to say that his write up is bad, just not exactly what I think I need...

I called Roger earlier and asked if he was selling these seals for 928. He mentioned that he got Haynes manual which apparently should have something in there, but I can only find one for 77-81 models...

mx22

Ok, step 1. Spoke with Roger and he suggested Haynes Techbook Automotive Heating and Air Conditioning Manual. Not 928 specific, but fairly cheap on Ebay - so I went ahead and bought it...

Don Carter

I'd say start simple. Look for the leaks first. Usually there is an oily residue left by the leak. You didn't say if you had rear air, but if the rear expansion valve is leaking, it will leave an oily mess under it. Just pull off the rear cover, easy to check. Also look at all the seal points, under the passenger seat, both inside and under the car, and there's another near the passenger fire wall. Another common leak point is the hoses from the compressor, so look for oily residue where the rubber meets the metal.

It's also possible someone else already put dye in it, so a common black light can be used at night to look for the dye.

I second the nitrogen suggestion. Even though you should replace all seals while your in there, you do have a specific leak, so best to find it before opening up the system. If you pump up the system to 80-100 psi, you may be able to hear the leak.

If you have rear air, you have two expansion valves. They are cheap and leak quite often, so replace both.

It's a great idea to DIY, since AC work is so expensive. You can find rebuilt vacuum pumps on ebay fairly cheap, and R12 gauges can be had fairly cheap at pawn shops.

Good luck!

WallyP

Go to our web site;
928 Tips & Links;
Wally's World;
The HVAC System.

bigmac

It can be a bitch, Had my usual shop redo the compressor and finally took it to Local P dealer who redid the lines with original P parts. Works like a dream now. Good luck, Mac

dr bob

The tech parts supplement from Porsche (included on the Morehouse CD set IIRC) has the diagram and locations sizes of the o-rings you'll need to replace. DO THEM ALL, without fail. There are a couple that are tougher to get to, like the ones at the fuel cooler, but you really need to get all of them. Then evacuate and see if it will hold vacuum (a test for Large Leaks). Do a full evacuation and leave the pump on for a while, overnight if you can. Check vacuum again before you charge. The dyed charge will help you find subsequent leaks, but everything needs to start out really clean. The traces are then visible under black-light.

mx22

Well, I'm surprised there is no diagram in the workshop manual - at least couldn't find one with a quick glance. Can anyone upload it in here?

WallyP - thanks, I already have that printed out. Just need some visual guidance now...

Thanks!

mx22

Bump... Someone must have a diagram of all of the o-rings...