Shark-bite

I was thinking about converting my R12 A/C to R134. My plan was to purchase a complete set from Griffiths.com. this set included drier,condenser,exchanging valve, compressor and in/out hoses that goes from compressor. I was wondering if anyone done this before? Please help need all advices I can get..I don't know much about A/C.

Compressor about to come down yet til i get replacement.

Constantine

Have used Griffiths products in the past, AC and his rebuilt steering racks, with great results. Have also talked to him by phone on a few occasions and he is very knowledgeable about the AC systems in 928s as well as other Porsches.

Don't believe you'll have any problems with his product line.

Shark-bite

I don't know much about A/C. Can this set be plug and play? I spoke with someone Griffiths.com couple times and I even make it clear with the Rep that if I screwed up. I will deal with it because I am not certified ACguy. I just need a complete set that plug and play. I can remove and replace..

Mrmerlin

Wowah I think you need more wisdom before you dive in.
Firstly what are the issues you have with your current system?

JBT3

@Shark-bite Welcome to Rennlist. You're probably going to get a lot of different opinions on R-12 vs. R-134. It's been debated many times with smart, knowledgeable members taking both sides. You need to read and decide for yourself. There are a lot of existing threads on the forum about the system and the switch you are contemplating. The Rennlist search function isn't the best so suggest you use google to search the site. Like this (site: rennlist.com/928 "search term"). A few examples to get you started:

https://rennlist.com/forums/928-foru...e-install.html
https://rennlist.com/forums/928-foru...n-83-928s.html
https://rennlist.com/forums/928-foru...2-to-r134.html
https://rennlist.com/forums/964-foru...ion-steps.html

My 2 cents: a PO had paid a shop to convert by 928 from 134 to 12 and they obviously messed it up because it never worked right afterwards according to the repair paperwork that came with the car. They likely didn't drain and flush the system / change out components as they should have. After much reading, I'm personally planning on switching my system back to R-12, but only properly with a shop that knows what their doing and actually cares about doing the job right.

Bill Schmaal

My 1987 S4 got the Griffiths R134 conversion kit several years ago and it is a great kit. However, I did not do the work myself so I cannot vouch for any difficulties in the process. But Griffiths is very helpful if you get into trouble.

Bill Schmaal

GregBBRD

Because of the high cost of a proper R12 to R134 conversion, it is very rarely done correctly.
And the cost of "redoing" it, after it being improperly done is even more expensive than doing it correctly, in the first place.

A R134 conversion requires the system to be flushed. The "rub" about this is that the system can not be flushed with the expansion valve (valves if one has rear A/C), the compressor, the dryer, or the rear A/C switch (if the car has rear A/C) attached.

This means that virtually every junction in the system needs to be disassembled (which is handy for replacing the R12 "O-rings to R134 "O-rings) and individual components flushed.

We have a professional flushing machine, which helps this job go quicker and less "messy", but this part of the job takes 5-6 hours....for a trained tech to do.

At that point, one can replace the compressor, the dryer, the hoses, and the expansion valves (don't forget that small hose from the condenser to the hard line on the right front side....it leaks more often than any of the other hoses.)

It's important to realize that some of these systems have been sitting for 30+ years, without Freon. And some of these systems have been sitting for 15+ years with R134 oil mixed with R12 oil...not functioning.

At this point, the system can be evacuated and left to sit for 12-24 hours, to see if the system leaks. (This step needs to be done as quickly as possible or the desiccant in the dryer will be ruined. Depending on how many leaks and where they are, we may replace the dryer a second time, just before charging the system.)

If the system holds vacuum, the next step is to pressurize it, with dry nitrogen, and let it sit for another 12-24 hours.

Once the system passes both the vacuum test and the pressure test (amazingly rare on a 40 year old 928), it can have the R134 oil added and be charged. (Leaky condensers are amazingly common. Leaky front evaporators are becoming more prevalent. Leaky rear evaporators are so common that finding a good one can be a big issue.)

And once the "Freon" part of the A/C system functions, you MIGHT get cold air...if the electrical and vacuum part of the system works! (Which is a completely separate problem, from the "Freon" part of the system.)

Long story short:
This is not a "quickly done" or "cheap" undertaking and a "kit" rarely solves all of the issues.
If you are doing this yourself, at home, you will need to plan ahead for several lunch breaks.
If you are paying someone who does this job properly, it can easily cost 2K, BEFORE the vacuum/electrical portion is addressed.

Mrmerlin

NOTE when adding flushing fluid to the AC system,
you then must replace every O ring that the fluid has contacted,
as the fluid will swell the O rings where it pools at the joint ,
and then the O ring will leak.\
I usually flush the lines and the components separately,
then blow dry,
then fit new O rings.
Usually when a shop works on a car to convert it or recharge it,
they add oil and sometimes the oil added is not compatible to the original R 12 mineral oil,
or the PAG and Ester oils dont mix either.
NOTE this then spells the end of the compressor in short order,
usually a thrown off belt or loss of cooling is experienced.

NOTE or a DIY owner goes and buys some R 134 and puts it in and this charge has different oil in it ,
this then smokes the compressor and contaminates the rest of the system.

BTDT

GregBBRD

.....Many times.

Petza914

I'd get the system working with R12 since that's what was in there.

You'll need an AC gauge set for starters.

For R12, at 70 F, you want High Pressure no higher than 180 and Low Pressure around 30

Eplebnista

I put together a guide to 928 AC service for last year's frenzy, A copy of it is HERE.

It's fairly comprehensive and contains some accumulated wisdom from threads here and properly attributes Mr. Brown and others who have graciously shared their knowledge.

It isn't rocket science but doing it right takes time and investment in more tools. IMHO the number one problem (once you know your heater valve is working as it should and all the under dash diaphragms are intact) is you have no idea what sort of junk the previous owner(s) may have put in the system. Robust flushing is essential.

The Forgotten On

I've done it in my 89 S4 after the previous owner had a bad conversion done and locked to compressor up. Sent aluminum shards through the whole system, you get the idea.

Realistically you will need a rebuilt compressor, either OEM or Griffiths, they both work extremely well.

Then as stated above you will have to replace all o rings, hoses, and the expansion valve(s). The valves will make the biggest difference as the orifice sizes are different between the R12 and R134 versions IIRC.

A new drier is a must any time you open the system.

Any competent AC shop should be able to rebuild your existing compressor hoses with barrier hose for ~$100 or so if you decide to stick with an OEM compressor. The Griffith's kit will include all of this.

But flushing takes forever to do with an air compressor and a flush gun so you will need to take your time doing it right. Then you should be rewarded with ice cold AC.

Eplebnista

IIRC 928 expansion valves for r12 and 134a are identical. In systems using an orifice tube instead of an expansion valve the orifice tube must be changed. Expansion valves vary the orifice based on refrigerant temperature.

mj1pate

There’s little I can add to posts by the esteemed members above.
I’ll mention that I’m in the middle of the same operation.
Lots of R12 snot-oil is sitting in your under-chassis ac lines that feed your rear AC. Drop them and flush. Flush every component separately and force dry with dry compressed air.
I suggest NOT ordering the minion of orings from Griffith, as it seems they come in a big mixed bag. Make a list of oring parts and send that list to Roger. He bags each type separately. DONT skip replacing each oring. Order plenty of spare orings. You’ll figure that out once you get into this job.
You can rent this thing:



lots of YouTube’s on how things things uniquely help and can save hours in finding that leak that BigBlu and stethoscopes can’t locate. To the admin: I’ve no affiliation. There are other similar, quality ultra-sonic sensors. Just use one.
good luck!