FeedNfrenZ

What is the easiest way to tell if your AC system has been convered from R12 to R134a?

Pizza

Bring it to a local AC shop and pay them $500.00 to tell you. Tight wad!!!

FeedNfrenZ

Watch it! Remember............. I know where you live and I need new tires!
Check your PM.

ErnestSw

The fittings for R12 are smaller than the ones for R134a. An AC shop will be able to tell you by looking at them.

ew928

On my recently converted shark,
them mechanic boys put on a RED shrader-type cap on the
evaporator. Noticed that on Chris Lockhart's car too.
His is 134a. But his is also a very red shark.
Don't know if he did that to match colors.

I second ErnestSW's recommendation to let the pros check.
Don't even want to figure out the cost of decontaminating
a shop's A/C recovery system.

Ernest (NYC) (The other Ernest)

ErnestSw

The red cap goes on the high pressure side and the blue cap goes on the low pressure side and is hidden under the hot connector on the right front of the engine compartment.

MBMB

If the fittings are schrader valves (like on a tire -- you could hook your bicycle tire pump to them [DON'T DO IT!]), it's most likely R12. If they are larger, it's R134A.

fst951

Most decent A.C. shops have a simple gas tester. They cost about $1k, but helps to avoid cross contamination. Don't use the fitting test to judge refrigerant. Go to a good reputable a.c. shop....they don't need to specialize in Porsche, and it may be better if they don't $$$$. I takes about 5 minutes for them to tell with there little hand held tester.

Good luck.

fst951

I had a small robinair unit that weight about 10 lbs. It tested for R-12 and 134a. I bought it used a couple of years ago for about $800 and sold it a little while ago for the same money roughly-part of a trade. I suspect now they would be available for about less than $1000 new. I believe that all it does it check for flourinated vs. clorinated halogens. I doesn't need to be a full sized mass spec. or gas chromatograph. I have seem that at a number of shops. I really must admit that I didn't buy it new and I got it with some other equipment like scales, etc. It isn't fool proof and it doesn't tell you percentages, just go and no-go basically.

dr bob

While the valve inside is indeed a schraeder-type, the outside of t he R-12 fitting is a bit larger than a tire valve. Meanwhile, the R-134a fittings have a very similar valve inside, but the outside of the fitting is a cam-lok type with no threads showing. maybe the best way to tell the difference might be to see if there are threads on the ouside of the fitting when you take the cap off.

I used the screw-on retro-fit R-134a fittings when I converted my S4 to R-134a. They are pretty obviously add-on fittings. I could snap a picture and post it if that would help in identifying what you have installed. As others have noted, the R-134a fittings also have color-coded caps on them, vs the black caps that the R-12 fittings have.

A diligent technician would have installed a label over the original label, with the charge info, and should also have a date and the installers name on it.


Many home-grown 'conversions' ignore some of these "conventions" so there's always that element to consider.


Are you thinking about using R-134a? The reason most folks start thinking about it is because the old charge, whatever it is/was. has leaked out. So you get to find/fix the leaks, evacuate and recharge the system, etc. If you are going to R-134a when you are done with your repairs, the list of things to add for r-134a is quite short-- you use a different oil. Other than that, a reseal of a system for R-12 is amazingly similar to a reseal for R-134a: New o-rings, new rubber sections on the hoses, a new drier, these are common no matter what refrigerant you'll use. For R-134a, you'll want to drain and flush the old oil from the compressor and put in new polyolester oil to replace the mineral oil that was in there.


While it's possible to DIY a lot of the mechanical part of this work, most folks would do well to leave the final evacuation and recharge to someone who knows what they are doing. That person is also likely to vae some leak detection tools that the DIY guy may not want to afford for a one-time effort. Several locals here in the SoCal group have done thier AC work this way with good success.

FeedNfrenZ

My problem is the A/C gets cool but not cold. I can see a good bit of bubbles in the sight glass. I am fairly certain that the system is using R12. I had intended on just boosting the R12 and seeing what happens. If it got cold then in a few weeks started getting less cold I would see about having it checked for leaks and/or converting to R134. Since finding out that I can't buy R12 without a license my new plan is to bring it to an automotive shop, have them put a sniffer on it and recharge it with R12 if they don't find a leak. BTW I did check the vacuume lines with my Mytivac. They all tested okay.

fst951

Dr. Bob,

You may want to check, but Sanden and Nippon-Denso who make the majority of the compressors for the 928 recommend that you use PAG-46 or PAG-100 when you do your conversion to R-134a. You must flush the entire system to get rid of the mineral oil. I like double end capped PAG the best. Ester is alright, but foams a little more and is not recommended for these compressors. I am sure it will work, but probably not as well.

Good luck!

FeedNfrenZ

1 can of R12, no leaks...................... Chillin!

fst951

No. You probably introduce 1/10 of a percent of air when you first hook up. Realize as well in most a.c. reclamation equipment they only filter to about 99% anyway and the drier hopefully gets the moisture, but it won't get the dry air. The little hand held units work well for most needs. 1% contaminate of R1-134 will decrease cooling about 3% and raise head pressures about 2%. That has been my experience with contamination. If it really matters, who can tell. What do you think about the oil info I posted?

Thanks

fst951

I know about dessicant driers. You use similar units to tread paint air. I have had good luck with them over the years. Simple and cheap. Yes if it is unused, that is not contaminated with oil etc, water can be baked right out of them. I just always replace the filter driers because if you ever open one up, you will find a fair amount of compressor fine shavings in them.

There are locations where you can get mainly dry air, like carlsbad, ca or central mexico, or even here in Utah. 10% and less humidity isn't that uncommon for a day or two out of the year. I use Ritchie Engineering Brute Guages and pull vaccum down to about 1000-500 microns at this altitude, but that still leaves a little air. I like to crack the input line prior to charging to allow the air out of the feed hose. It looses about 1/50 of an oz of freon, but purges the system pretty nicely.

We don't have to agree, thats fine. Double End Capped PAG is the finest compressor oil on the market for new systems. Ester has its place as well, but not in a new Sanden or Denso 928 unit. Highly refined mineral oil is also an oldie but goodie.

Thanks, Doz for your input. I am sure that we will argue and agree in the near future.

Take care!