Cameron

1987 S4 Auto.

I have had this baby for 13 months. I have put about 8k miles on her in that year. She is up to 25k total miles now. This week, I had my first real mechanical issue. The AC stopped blowing cold.

Diagnosis. She had lost her freon.

I found a place that would recharge the system. I know that this is only a temporary fix. Will it last 1 month, or another 28 years?

So here is my dilemma. When the problem presents itself again, do I keep and recondition the R12 system (find the leak etc) or convert to R134a? All experiences are appreciated.

If you changed over, did the R134a system blow really cold? I am in South Florida and it is freakishly hot and humid here for 8 months. The R12 system is really ice cold and i am a bit worried about going 134a. Can I use the existing compressor or do I need to get a new one? Etc.

Let me know what you did, especially folks in the deep south and Florida.

Thanks

MainePorsche

First, leaks can be fixed.
Conversion to 134 does require some work and components. Not just a flush and fill. If I remember correctly new O rings, dryer, condenser, and expansion valve required. R12 is apparently becoming hard to find. I remember on my old 86.5 I had a hard time finding someone with it, and they sold the recharge in its weight in gold - this was years ago.
As to the coldness of 134, my 87 was retrofitted by Porsche courtesy of the PO. I keep it tuned very well and have to say it is very cold. I occasionally have to slide the temp up a little when on the freeway for it gets to cold. I'm in the Northeast but we do get hot and humid though not as continuous as you have it.
Do you have quality window tinting ? As the 928 has ample glass at every angle to allow infrared ingress and heat retention while parked or driving protection against this is a good idea. 3M has a product designed for infrared protection that I'm going to go to.

Add: SeanR had a good thread on the subject. Below is an excerpt from Dave M.

To do the conversion absolutely correctly you should flush each system component, change all o-rings (maybe 20 or so), rebuild hoses with barrier type for 134, install ester oil, new receiver/drier, evacuate and recharge with roughly 80% of the r12 weight in r134. You need to add proper oil to compressor after removing old oil. You might upgrade your condenser, expansion valve and change pressure switch to a 3 way.
OTOH some people take their car in for a quick conversion which is recover old r12, evacuate system, and recharge with r134.
If you care about long term durability, choose option 1.
Good luck,
Dave

Shark_gts

Red Tek! www.redtek.com They make a conditioner type sealant, and a major hole sealer too. And for recharge an R12 direct in replacement, no need to convert if I recall correctly. There is a charge kit too.

We've done 2 cars with Redtek, just using the gauges. Both cars took 2 cans and are making ice cubes!

dr bob

The effort and parts needed to reseal for secure R12 use are exactly the same as needed for r-134a. There are some amazing debates on performance. I sealed mine and converted to R-134a in 1998, and have enjoyed excellent system performance. In SoCal with low humidity and the freeze switch failed in the bypass mode, center vent temps less than 20ºF with fan on 2 and 60 MPH cruise. Freezes fingers on the wheel of the black car.

Later in life now with less frequent use, I have a slow compressor seal leak that shows up if the car sits for a few months of non-use. I put about 20oz of R-134a in it at the beginning of last summer, after the winter hibernation. I guess I need to drive it more, or at least reach down and rotate the compressor shaft a few times during storage.


On AC stop-leak products... Don't. The expansion valve looks a lot like a leak to any sealer.

Cameron

Doc,

Thanks for the recommendation on the stop-leak products. I have to admit I was considering trying some.

Sounds like your 134a conversion was a huge success.

The redtek is an interesting read. It sounded like you could just add it like R12, but then it says not to mix with anything else (R12 or 134a). Has anyone else tried it out?

LT Texan

I rebuilt mine with barrier hose, new expansion valve, green o-rings filled it with Freon and never looked back.

It hasn't needed any more freon in 5 or six years.

bureau13

I think the first thing you need to do is find the leak. Depending on where it is and how easy it is to fix, it might not be worth it to bother with updating for 134a.

My AC arrived non-working, so I replaced the compressor, expansion valve, a bunch of o-rings and I had a new dryer ready to go in but I still had a leak. I had to declare defeat and take it to an AC shop, and they found and replaced a leaky hose. They also went ahead and upgraded to 134a. It's working...I wouldn't say it blows ice cubes. It's perfectly fine most of the time, but sitting in the sun on a hot day, compared to my H3, it's not nearly as good. Is that due to the 134a? The fact that it's a 1986 AC? Or possibly, the shop didn't do a great job pulling a vacuum, etc (one of the problems with declaring defeat and taking it to a shop...you don't really know what you're getting, if you're not intimately familiar with said shop).

But anyway...I would recommend finding that leak first...

Bertrand Daoust

The easiest way is:

Find some R12 and recharge it.
It will be good for a while. But for how long?. Never know.

Or, make a leak test and correct the problem.

And recharge with R12 or convert to R134.

Converting to R134 involves, looks like it, quite a bit of time.

Never been there.

But when mine went south, I just recharged it (R12) and it is still good after three years.
Didn't cost much and didn't take much time either.

Just saying...

bureau13

I guess the risk is if you do that without understanding your leak, you may have recently sprung a big leak and you just flushed $100. If you do a leak test first, you can then make a more educated decision on whether it's acceptable to just refill.

WallyP

My suggestions:
- Make a determined effort to fix any leaks.
- Decide on R-12 or R-134a. Don't use anything else. It can be difficult to find a shop that will work on anything other than one of these two. If you don't tell them you have a "sooper-dooper drop-in replacement" and their recovery system gets contaminated, you could end up paying for the decontamination. Use the proper oil for the system. Mineral for R-12, POA for a factory R-134a system, and POE for a conversion system with R-134a.
- Put in a new receiver/dryer.
- Don't use any sealant of any kind in the system.
- New green or blue O-rings on the entire system are a good thing.
- Pulling a really hard vacuum is a good thing.
- Flushing the system is a good thing.

Cheapest and easiest - Fix as many leaks as you can, put on a new receiver/dryer, pull as good a vacuum as you can, add POE, add 80-85% of specified capacity, using R-134a bought at Big Lots for $6 a can. Buy some extra...

Cameron

Yes, I did drop the coin to refill it. The shop didn't have time to troubleshoot the leak yesterda. My options were to refill and take a chance on flushing a hundred dollar bill, or schedule and bring it back. Because it has been working for me for 13 months, plus the PO for years before, my thought process is that it is a slow leak. But I understand that I could turn it on this morning and I would be back to square one.

So I refilled it and am now researching which way I will go when it is empty again. Yes, finding any and all leaks will be part of the process of a more permanent fix next time around. One reason I am leaning toward R-134a is availability. It's not easy to find R-12 and shops to work on it. But my biggest concern is that the AC on this car is ice cold. And that is really really important to me down her in South Florida.

Thanks for all the advice, guys.

bureau13

Roger still has R12, but you need your 609 certification to buy it (If you have 30 minutes, a few bucks and an internet connection, you too can be 609 certified )

j.kenzie@sbcglobal.net

BTW Ester oil works with R134 and R12.
Dave

Shark_gts

R12 is no longer legal, ozone depleting chemical. R134a conversion is no picnic either, very small molecule, R12 seals aren't compatible (ie leaks out) so you have to change them all. I had a conversion done on an 87S4 & it was marginal.

Solution is Redtek. Call them up, talk to one of their engineers. We used the stuff in an R134a system (Audi and and a Volvo)

bureau13

R12 is NOT illegal to buy or use. It is illegal to manufacture.