Nicole

I had been wondering why I had intermittened AC last time I drove the car.

Well, today I heard the dreaded "escaping gas" noise from the center vent, which stopped when I turned off the AC, and came back when I turned it on again.

Third time - and hopefully the last. Now I have to look into a permanent fix. Dash out, evaporator replaced, all WYAITs, etc.

I'm trying to figure out, if I can complete this between Sharks in the Park and Sharks at the Lake, or need to take the car to the local specialist (San Carlos Radiator).

I also need to figure out whether this is the time to convert to R-134.

Any thoughts, advice, and moral support would be appreciated.

928Quest

Don't convert. Won't work as well, My Slate gray '91S4 was converted and did not work as well as my GT does

Brian Felts

I don't think the R134 is as cold either. I didn't know if it was just me or others felt the same way. What else can you do if you need refilled with R12


Brian

ColinB

Hello Nicole
I was going to do the R134 conversion last January but I haven't had enough time at home to get it done yet. R12 is now banned in S Africa so I had my VW Microbus converted about 2 years ago and I have to say I can't tell any difference. Critics claim that the R134 is slightly less effective but all that means is that the AC has to run a little longer to lower the cabin temperature to the same point.

As an alternative, one of the UK Rennlisters also referred me to Isceon 45, a DuPont refrigerant that is marketed as a direct (no mods required) replacement for R12. I haven't investigated this properly yet but it's available where I live and it sounds promising.

Colin. 89GT.

John Speake

R413-A or Isceon 49 are also reputed to be R12 equivalents.... so I have been told.

linderpat

so that's why the ozone hole got a little bigger over the weekend on the west coast

Nightfly

Both cars, 928 and Bronco have been converted to R134. Bronco is all black (gets HOT HOT HOT in summer), and still gets nice and cool shortly after the a/c is on with the R134. I've only had the shark since last november, so I can't really tell yet wht it's like on a REALLY hot day, but test drove it ilast September on a 90 degree day and it seemed fine (but it has the rear a/c too).

Mrmerlin

Nicole if you go the regas route be prepared to also repace all of the O rings at all of the pipe connections, the compressor needs to the be removed and the oil changed and usually this also includes replaceing the reciever drier ( the round tube looking thing on the front of the condenser) and the expansion valve/s ( thats 2 of them if you have rear air).
A big job to say the least, If you opt for the Freon then you will only have to replace the broken parts and then refill ( the refill could be expensive). It would also be a good idea if the system is empty to replace as many of the O rings as possible, plus the reciver drier and the expansion val;ves
If you do the refill I would also make sure that whomever is doing this also adds some oil to the system as the original oil usually leaks out over time, this can be confirmed by the bottom of the compressor being oil coated or just having a lot of dirt on its bottom and then if you have rear air the bottom of the car being dirty around the piping connections.
If you remove the dash its a good idea to replace the vacuum pods since you will be in there. I dont want to volunteer anyones help but i would recommend that whomever does this job has removed a dash in a 928 before they get to your car, Im thinking Bill Ball would be a good choice as he is thorough and cognizant of the proceedure to do this.
If I was closer to you i would assist you on this task......
As far as the 134 it doesnt seem to get as cool as the freon and it will have to be run at a slightly higher pressure to get similar cooling results.
When i rebuilt my car I redid all of the hose connection seals and replaced everything that i have previously mentioned, and also installed a new compressor and then refilld the system with Freon

Anyway are you sure the freon has left the sytem its easy to check just turn on the A/C and look for the sight glass on the top of the reciever drier, (This is in front of the front radiator on the passenger side, it look like a little tube about 3 inches in diameter and about 7 inches long))if it looks like a liquid flowing through then you may have another problem if all you see are sporadic bubbles then the system is just about empty ( any chance you have a vacuum leak?)

borland

Your gas milage will be reduced with R-134 as the compressor needs to work harder. R-12 is more efficient.

ROG100

R12 is readily available so stick with R12

928fan4life

try this stuff

http://www.redtek.com/home.html

I have used this in my vw's and it blows a little colder.

Daniel Dudley

Freon is a larger molecule than 134a. The seals and hoses on a 928 can retain freon longer. You supposedly should at least update the seals on your compressor to switch over. I haven't done it, but I understand Griffiths makes the update.

FWIW, I would stick to the old stuff, but my AC has already been converted on my 85, and it is fine. It is however critical to maintain close to optimal fill with 134a, as cooling efficiency decreases a lot with a slight loss of coolant as opposed to freon where you can loose a lot and still maintain a degree of efficiency. Earl knows a lot about this stuff. I just repeat what I hear.

soupcan

At work we had debated the R12 vs 134 to death, so about 5 years ago we toke two of our 1984 S-10 hanger trucks and recovered the R12. We then added new fittings to the lines and recharged them with 134. We did not change anything else. The outlet temps before and after were the same. Those two trucks went on auction last month and still blew cold air. I am not recommending anyone do this, but we did cause we just can't leave thinks alone. Did you know that a Goodyear Regatta 2 will explode 20psi sooner than a Bridgestone Dueler.

dr bob

Nicole--

Before you panic, have the system pressures checked with a set of gauges. The gas noise is typical in a properly running system as you hear the liquid refrigerant flash to vapor in the evaporator. There are some vacuum system noises around the center vent and the defrost vent actuators that might hiss on actuation. Let the gauges tell you what really happened.

For all the R-134a non-believers: My center-vent temps on 80+ degree ambient days, cruising with engine at 1500 RPM or greater-- 19F with fan speed set on '2'. Freezes the fingers on the wheel. The "capacity" difference shows up in higher pressures needed to get the refrigerant to condense when ambient exceeds about 90F. That just means that proper fan operation is critical, and the right pressure safety switch is a must.

Borland, if you can see a consistent change in fuel mileage, you have better and more accurate instruments than I've seen in most cars. The difference in NPSH at the compressor is negligible to the point where it's insignificant.

My two cents, based on over two months of experience with vehicle AC systems.

dprantl

Wow, lots of mis-information about R134A in this thread! Yes, the performance of R134A is less than R12, but it's not large enough to make much difference if the conversion is done right. The 928's condenser size ratio to interior cabin volume is very large compared to most other cars. Yes R134A is a smaller molecule than R12, but if you rebuild your two compressor hoses with barrier type hose (and all the o-rings with green ones of course) you won't have any problems. Fuel economy? Are you serious?

Dan
'91 928GT S/C