Ron_H

Dead compressor. All other parts in my system are good or almost new. Changing the compressor means a new drier to go with it I understand. I have two compressors, one of which hit the road hard enough to crack the support ear on the case, so I'll toss that one. The other one was working properly when it came off of the donor car 2 years or so ago, but it has been sitting in an unsealed box for all of that time. So I worry about that one too.
Rebuilt ones cost mucho dinero = more pain, and the pressure is not so great now since Fall is almost here in California. (mild days and nights until November)

So along comes this guy with a new type of compressor kit for R134 and swears it will freeze me out of the car. Being a hothead, I really need AC to cool off, and I listen to this but wonder if it really works. (????) All I hear is that it isn't as cold as the R12. This kit is expensive, but all will be well for years to come I'm assured if I use it. I'm already broke fixing the compressor and installing a belly pan to prevent this from happening again, and need to heal my wounds this week.

Does anyone have any positive recommendations for R134?

MikeN

I have always said that if you have a major breakage in the A/C system only then would I even think about changing to R134 and that would even be a reach. I'm afraid there is no cheap way out of this as both the new kit or the repair of the old system will cost some money......and nobody can make a
statement that such & such system will be great for years.......a true long shot.

A proper changeover to R134 will mean flushing the system, replacing the soft lines, drier, O-rings, and most likely the expansion valve(s) if the compressor grenaded.......no small task on a 928.

There are some here that have had good luck with converting to R134......but every trusted 928 mechanic that I have ever talked to about the subject always frowned on it. Fixing and refilling a R12 system yourself is just not as much money as people think. If it were me I'd take the compressor that is sitting on the shelf and have it rebuilt by a professional, flush the system (if the old compressor sent crap through the system) replace the drier, all O-rings, and expansion valve. Vacuum it down, fill it up with R12. The most you should have to do after that is top it off every now and then.....no big deal. Get a good deal on rebuilding the compressor, use a generic brand drier, clean the expansion valve if possible and get the R12 off of eBay and you can probably get by for a lot less than the kit would be.

Ketchmi

There is no longer any real money savings with R134a. I recommend that you stay with R12. It is easier on the compressor and gets colder.

Good luck.

deliriousga

Where do you get R12 system test stuff or refridgerant to DIY? I was told the R12 is up to over $100/lb. I didn't want to change mine over until I heard that. If I can DIY, I'd rather keep the R12 since it's so much cooler.

touque

John - try http://refrigerantsales.com/

Currently, R12 is $29 per can (free shipping with their prices) and cheaper if you buy more. They have an alternative called AutoFrost which is $12 a can and is really, really good (I use it). It's non-flamable and much different and better than Freeze12 or other common alternative coolants. http://refrigerantsales.com/autofrost.html

if you want to buy these, you'll need to be EPA 609 certified. You can get more info at http://www.imaca.org/.



Troy

p.s. I am not affiliated with these guys, just a happy customer...

Ed Scherer

You can get your EPA section 609 certification via Mainstream Engineering's on-line exam. Once you get your 609 certification card, you're ready to roll on getting your R-12. You'll find a lot of options on eBay. I got 5 cans at $20/can from "john102561". There's also a lot of gauge sets, vacuum pumps, etc. via eBay merchants. I was happy with usatoolwarehouse, from whom I got a gauge set, electronic leak detector, thermistor vacuum gauge, vacuum pump, and some other MVAC-related goodies.

I just went through this routine over the last few weeks, and my shark is once again blowing ice cold again after I suffered through a few months of summer heat.

SharkSkin

The replacement should be fine. Just have them vac the system down thoroughly. Minimum is supposed to be 30 min IIRC but try to find someone who can vac it down for a couple hours +.

Since as you say the heat is not such an issue, why not try to run the spare? It won't actually be a workable spare for you anymore if you convert to a kit that provides incompatible hose fittings.... such as Griffith's. Might as well give it a shot... it's paid for, right? Or did you hock it for bail?

Oh, don't forget that the AC plays a crucial role in keeping your windows fog-free in the winter. It dehumidifies the air when you use the defrost setting.

Regarding the AC conversion, I've heard that the problem with most conversions in R-12 cars is typically not that it can't cool, but that the relatively small condensors in most cars can't shed the heat fast enough. R134 carries more heat than R12 so with an inadequate condensor the system saturates with heat more quickly then seems to work poorly. In fact, it's working too good at pulling heat from the car, not good enough at shedding it from the condensor! The 928 has a very large condensor and can be made to work fine, provided you get enough airflow. This is one of the reasons that later cars always run one fan when the compressor is engaged. You might consider adopting that feature. Also, the 928 AC system shuts down the compressor with a temp switch. Unfortunately, with R134 the head pressure can be way too high(200, 300psi) before the temp switch activates. One solution is to supplement that with a pressure switch to make sure pressure doesn't get out of control. I had a couple of long conversations with Big Dave at SCR about R-12 vs R-134 for 928's and in general, and later found supporting info online regarding this.

I have the Griffith conversion, and it is 3 or 4 degrees warmer than the R-12 was at the center vent. It was only charged with R-12 and dye for long enough to verify that the evaporator & condensor weren't leaking before I tackled the easy stuff. Anyway, that kit is fine as long as I'm moving or the fan is on. Also I notice decreased capacity at idle, but mostly I attribute that to the larger pulley on the Griffith compressor. It's not so bad that I've spent any time looking for a smaller pulley, but that might be an option. I think if I wire my fan to come on with the AC compressor I'll have no complaints, since the only time it seems less than adequate is stopped at idle with the electric fan off.

Save yourself some $$$.... put in the spare with some new o-rings, new drier, and go get it vac'ed and charged. Dave has a very sensitive leak checker, and can recover the freon if it's found to be leaking. That way you won't get charged for it and can reassess the situation. Leave the belly pan off so he can get to things without having to charge you to take it off and put it back.

Ron_H

Thanks for the replies. I have more options than I thought I would have. I still cling to the belief that the compressor I have as a backup and is on the car may be OK. (actually, that is the cheapest alternative) I will search for someone who can open it and verify it is clean and oiled. Otherwise I like the idea of doing it myself per Ed's suggestion. And I will stay with R-12 at this point, since Dave has scared me off of re-engineering my condenser, and I am too poor to do the Griffith's method.

Ketchmi

Hi there.

Griffith's kits are marginal, or at least they used to be. You could make your own for less, but don't bother. I just pulled one off a 944T recently and it was rinky dink. Screw down clamps back in the day. Stick with a factory compressor and R12. Blends suck since when they leak out, it totally changes the composition of the gas mixture. You wind up with uneven oil carrying capability as well.

You won't be disappointed.

Good luck.

Ron_H

Yep, the more I think about it, the more hesitant I am to go with Griffith's stuff. And my system with R12 was working so well before the Nevada trip I think it is a known and worth preserving.

BrianG

My Japanese spec car was changed to R-134 on importation, and it barely runs cool. Conversions just don't work as well as the original.

SharkSkin

Did it look like this?

Ed Scherer

BTW (and sorry, this is somewhat OT), but as I was doing my A/C work recently, I needed to dig up an R-12 can clamp and came across an old A/C recharge kit I probably got back in the 1980s. Check out the device next to the purple arrow. It was still in the box. Think I might be able to sell this evil thing on eBay?

IcemanG17

Since R134 has increased in price so much lately I also vote to stay with R12....it just works better. The cars were designed for it...might as well keep it that way. With a properly set up R12 system you can get really cold A/C....much colder than many new cars! In my car with the air intake set on fresh air (vacuum leak) I still get 50+ degree differentials to outside air!
Brian

dr bob

My R-134a converted S4 makes 22 degree air on 90+ days cruising, with the freeze switch failed closed. It will freeze fingers on the steering wheel. That's in my black car.

Take a look at the WSM pages that show the two graphs of center vent temp vs ambient. Notice the difference at 30C ambient (about 86 degrees F)? Darn, it looks like the R-134a is cooler!

Most 'conversions' yield poor results because they are not done correctly or completely. It's easy to shortcut on changing all the o-rings. Easy to leave the old expansion valve in. Easy to leave the old hoses in there. Easy to overcharge the oil. Easy to overcharge the gas. Easy to ignore the need to get ALL the air out of the system before charging. Easy to ignore vacuum system problems, heater valve leaks, blend door motor problems, evaporator cleanliness, etc. Ignoring any of these will cause you to have a system that underperforms.

With the cost and availability of R-12 getting easier, maybe folks will want to stay with it. But remember that there's a reason you are working on the system to start with, and that's because your old gas leaked out. Fix the leaks. Fix the leaks. Fix the leaks. Fix the leaks! Once that is done, S4/GT/GTS cars that were R-12 cars originally are good candidates for R-134a. Earlier cars with only one electric fan can easily justify staying with R-12, as it's more forgiving of high condenser temps than R-134a.