Mikebte

I have been running R12 in the car and my trucks for some time now,
Being as I am finally running low on R-12 and I want to keep my extra can of R-12 ( $$$ ). I am thinking of doing the R-152a conversion in the Porsche 928.
Has any one else performed this?
I have done it on a buddy's BMW and wanted to see if anyone else had any luck with it on the Porsche side, being an older compressor.

I know it works, but figured I would reach out and see what others have had luck with, R-134 is the norm. But I like new things.

ammonman

As I understand it the molecules of R-152a are even smaller than those of 134a so the issue of hose permeability in systems that have not been retrofitted to barrier hose will be even greater. There is also about an 8% energy penalty for using R-152a vs R-134a so this will rob more engine horsepower to drive the compressor. There are also questions of oil foaming issues when an dedicated oil separator isn't part of circuit design. Until there is more understood about the potential downside I would be leery of risking expensive 928 components.

Mike

Mikebte

Well,
The old compressor is good, and I have a new compressor to install.
I purchased 2 driers so I could try it out. Figured if it fails I will install a new compressor and drier and go to 134. But I figured I have had luck a few times, why not try again.
Worked on a 77 bronco, a few BMW's and a VW, may as well try on a Porsche.

As soon as I get back into town from Work I'll make it happen. At least before summer.

ammonman

I hope everything works great. Please be sure to post your short term results and any issues discovered.

Mike

Chris Lockhart

Good luck. I'm interested to hear your results.

Red Flash

Excuse me for maybe being slightly off-topic, but isn't that R-152-a, the stuff the European automakers have determined is a serious fire hazard and now refuse to use it in new cars?

Who doesn't want aircon? On the other hand, the it seems to me that regarding R-152a I would wait or if really urgent just do an R-134 conversion.

Mikebte

The EPA considered it a suitable replacement for R12.
And it is flammable, but so is gasoline.
It's what they put in can of air duster.

dr bob

There's some first-hand evidence of the flammability issue, demonstrated graphically at a OCOC dyno session in Wichita. An AC hose was ruptured by a belt that came off during testing. The escaping gas, an isobutane and normal propane refrigerant blend, caused a fire as soon as the escaping refrigerant hit the hot exhaust.

R152a uses a blend of hydrocarbons including methane, the principal component in common "natural gas". There are others with similar flammability. The challenge in any automotive system is how the various fraction molecules will pass through hoses, seals and such at different rates. The smaller molecules leak out first. Modern "barrier" type hoses and better o-ring seal materials work amazingly well compared to what was considered acceptable in original R12 systems. For those who remember R12 systems, a little "topping up" of the system every few years was considered normal for a long time. With a hydrocarbon blend, one would need to completely evacuate the old unbalanced blend before recharging a system, even if the system was only partially discharged via a small leak. No "topping up", effectively.

The Good News for the OP is that a new R134a drier, charged with polyol ester oil, can switch seamlessly between R134a and R152. And like R134a conversions, a complete system reseal, including replacement of all hose sections is needed. But with R152, replacing every hose section with barrier is an absolute requirement; there's no fudge factor or other allowance for minimal leakage through the hose sections that aren't easily accessed. You can install new hoses as crimp-in-place, or braze new fittings on the ends of the hardline in place, then custom hoses. Greg Brown offers this service if you can get to his SoCal shop. Absent this kind of reseal effort, you'll have fractions leaking out and doom yourself to full refrigerant replacement on a very regular basis if you want to maintain system performance.

No commercial refrigeration shop can work on your system for you if it contains R152.

-----

Like many who saw the R12 ban coming, I stocked up on R12 in cans and canisters, sure that R134a would never work as well in cars designed for R12. Soon after my 928 acquired me, I added R12 to overcome some from-the-factory leaks. Again. And again. Handwriting was on the wall that the car needed a substantial resealing effort. Once I committed to that, R134a with polyol ester lubrication was my first choice. If that didn't work well enough (black 928 DD in SoCal with no window tint), I could easily evacuate that and fill with R12. But R134a did work and still does more than adequately. I have added some after the car has been sitting a while, due to the type of compressor shaft seal installed in the original R12 compressor. Never an issue when the car was driven regularly.

So what should you use? My vote goes to R134a. Cylinders sell for less than $4/lb last time I looked at Sam's Club. Buying little cans is still an option, but in many places there's now an additional tax added to small can purchases. Buy a cylinder to use, and another to stick in the spares locker. If the EU and the rest of the civilized world decide that R134a production must cease, you'll have plenty for your own use, plus that other cylinder to market and pay for both.

And FWIW, R12 is still manufactured all over the world, excepting those countries that signed on to the original Montreal Accord a couple decades ago. The same companies that manufactured it here, like Dupont who owns the "freon" trade name, still make R12 in Mexico for instance. Theory is that you can buy canisters in Mexico for personal use, and just pay the import tax on it as you come back across the border. The "personal use" can be hard to explain if you are bringing 20# canisters back vs a few 12 oz cans for one vehicle.

I sold off almost all of the R12 I'd hoarded in the late 1980's. There are still a couple cannisters hidden in storage with the now-vintage cars and scooters back in SoCal. At some point soon while the economy is still inflating, all that stuff will be sold to other collectors and enthusiasts. It sure as heck isn't doing me any good, as all my cars are R134a.

Mikebte

The upside to owning my own AC machine, so I can vacuum and charge it myself.

I have had an AC hose cat has fire on a Peterbuilt truck while on the dyno, it also caught on fire with R134a freon. The oil in the system is flammable on any exhaust manifold at hot temp.

Good point on the R 12, I can always go get some and bring it back.

As for AC leaks, I would say from experiance that most leaks came from the front seal on compressors. Mostly as Dr Bob said, from sitting.

I find is crazy how difference and the same 134 and 152 seem to be.

I'll clean my system and let everyone know how it works. More of an experimental charge. It's just canned air. I remember when the canned air was R134.

I have a new compressor to install, but I'll see how it works before replacing the old compressor and replacing the whole system.

I'll check out that So Cal shop while I'm here, at least if I can get away from work long enough.

Mikebte

I wanted to end this forum with some info. I have chosen not to use R152 in my 928.
Here is why. While this is a great idea and I have seen it work, I have found that R152 evaporates really well with good air flow, it does just as well as R134 in traffic with a electric fan. My Friends who are running R152 run up and down free moving roads on a regular basis. while I get some stop and go traffic. The R134 has shown to work well in low air flow conditions. (or stock electric fan) For this reason I will be running R134 or R12. I'll update if anything changes.

Randy V

No need to end the forum, just the conversion discussion.

Mikebte

yup, that's what I ment. I'm such a newbie some times.

Randy V

A Newbie from Dewey.

Shark_gts

No reason to use the R12/environmental disaster stuff including hoarding behaviours when there is an off-the-shelf replacement & works for everything (R12/134a).

http://redtek.com/English/product.asp?ID=18

Exactly why aren't R12 system guys aren't all over this stuff?? I've posted several times before. We've used it in 3 cars works great. I don't get it.

Mikebte

Very interesting. I will read into the details of RedTek and maybe try it.