Converting A/C from R12 to R134a

arnebret · 07:40 AM

My car is still on the R12-spec (as far as i know) and must be converted to the new R134a, if i wish to use it anyway. To this the compressor should be opened, the oil should be let out and the a new receiver drier should be installed. The strange thing is, all the hardware will work with both R12 and R134a, the problem is the oil used to lubricate the compressor. The oil used in the R12 system will not stick to the R134a and as a result won't lubricate the system. So it's a matter of depressurize, changing oil in the compressor, replacing the receiver drier, fill the compressor with R134a-oil, and then pressurize with R134a gas. Problem is: WHERE do i get a new condensor and who can tear up my compressor??

slevy951 · 08-12-2002, 07:46 AM

Arne-

When I converted, I removed the compressor and let it drain on a bench for a few hours. Then reinstalled, vacuumed the system and installed new oil and r134.

I also got a new condensor from Griffith's Technologies. He has ads in Pano, Excellence, etc....

HTH

arnebret · 08-12-2002, 07:50 AM

Thanks, but is it possible to depressurize the system yourself, and then drain the oil out as well. I've been told working on the Airco involves quite a bit of knowledge. By the way is the new drier to be installed by yourself?

arnebret · 08:07 AM

Before we get things messed up here. What exactly is there in the A/C-system? I'm not sure what all the english names for the parts are. By compressor i mean the belt driven part, by receiver/drier (desiccator) i mean the 'can' that you can see when you look in the engine bay. I guess by condensor you mean the 'radiatior' in front of the car? If so, why did you replace that part and not the desiccator, or are we just having a 'name'problem here?

Scott R · Scott R's Garage

Your terminology is right on! But here are a couple of problems your gonna have here:

Not sure what type of climate you have in the Netherlands, largely due to my own ignorance, but where I live it gets above 90 all the time. R134A does not do well at these ambient temperatures.

Secondly you have an AC system that was built to use mineral oil and R12 refrigerant which takes less pressure to use than R134A. So for me I get terrible vent temps (around 50 deg F) in stop and go traffic in 90 deg weather. With R12 I get around 44~45F.

R134A takes more pressure and has different cooling properties than the original R12 so you get more heat off your condenser which translates to more heat through your radiator. This also means that the compressor is working harder to cool your car.

No on to "o-rings” to "properly" convert your R12 system
To R134A you will need to use "Esther Oil” synthetic based oil. This eats all of the old o-rings away so you will need to change around 12 o-rings.

4 for the compressor plate
2 Barrier hoses to compressor
2 for condenser side connections
2 Dryer
2 at the firewall and one or two more at the evap core (can't remember)

So based on a recommendation that I had from this board I removed my R134A conversion and went back to R12. Of course it’s illegal in some places but people still have it sitting around.

No R12? Anywhere? Then go to a R12 based clone like "Duracool” same cooling properties and it runs with mineral oil. Consider this before you make the jump to 134A

slevy951 · 08-12-2002, 10:17 AM

Quote:

Originally posted by arnebret
Before we get things messed up here. What exactly is there in the A/C-system? I'm not sure what all the english names for the parts are. By compressor i mean the belt driven part, by receiver/drier (desiccator) i mean the 'can' that you can see when you look in the engine bay. I guess by condensor you mean the 'radiatior' in front of the car? If so, why did you replace that part and not the desiccator, or are we just having a 'name'problem here?

I did replace both. Receiver/dryer and condensor. You've got it right.

I'm going to slightly disagree with Scott above. The r134 does cool as well as r12. It'll still get cold enough to keep me cool here in OK at 110F ambient. It does take longer to cool down than r12 IMO.

Scott R · Scott R's Garage

I guess it depends on what you like to see for a vent temperature. I like to see around 42~43 deg F. I can only get about 46~47 max on 134A. Plus I just hate to see my temp needle creep past 1/2, the 134 exchanges way too much heat for me.

divezic · divezic's Garage

arnebret-You mentioned in your original message that you need a new condensor. If there is nothing wrong with your old condensor, you do not need a new one for the conversion.

Also, according to the Porsche technical bulletin for changing freon systems, you do not need to change all of the O-rings. You must change the o rings on the new receiver/dryer.

The following is a link to a great web page that has a link to all of the 944 models' freon conversion technical bulletin (TSB 89501). There are a lot of opinions out there, but I'll trust the Porsche engineers.

I'll give my opinion, though. Replace the compressor with a new aftermarket compressor such as a Sanden if available. I've seen a few friends' cars blow a compressor seal. I believe with the higher operating pressures of the R134, this is inevitable on an older car.

arnebret · 08-12-2002, 10:48 AM

The temp here will come above 90 for about 7 days a year. Normally it will be around 80 in summer with quite a lot of humidity. So to get extreme cool air in my car is not that important. I know that R12 is illegal here, in such a way that companies may never refill a/c systems with r12.

The thing is, my a/c isn't working anyway. I still have to get to the problem, i think the system is a bit low on R12 and as a result i will not run it to avoid lock-ups. Though, i spoke to a spec and he told me that R134a is no problem for here and that only o-rings that will have to come out anyway need to be replaced.

But still, i have no idea what needs to be done on my compressor. If it has locked-up, i think i will just take the whole system out, as i'm not planning to replace the compressor and drier AND flushing out the whole system with special stuff. So i just hope it's something like the clutch or another very simple thing on the compressor, else the a/c is a goner and i will take out all parts.

btw: when i wish to remove my compressor can i just undo the lines that run to it, or should there be a special procedure to drepressurize the whole system before a line in the circuit can be opened.

Scott R · Scott R's Garage

NO do not just open the lines. The Netherlands is bound to the "Montreal Protocol of 1997" this was an agreement by 27 countries in the EEC on how to handle CFC and Halon based checmicals.

So that being said you need to have the old R12 vaccumed down to atmosphere and sent to a recycler or proper disposal facility. Your mechanic should have the equipment to do this. Venting R12 or R22 destroys the Ozone.

Sorry for the little history lesson. It was part of my MVAC license exam.

slevy951 · 08-12-2002, 01:00 PM

Quote:

Originally posted by Scott R
I guess it depends on what you like to see for a vent temperature. I like to see around 42~43 deg F. I can only get about 46~47 max on 134A. Plus I just hate to see my temp needle creep past 1/2, the 134 exchanges way too much heat for me.

Agreed on the vent temps. That's why I think it takes longer to really get the air cold in the car than r12. As far as the heat exchange, that's why I put in a Griffith's condenser. He makes them more "open" and free flowing than factory so the air goes thru better. I sit around 1/2 on the temp gauge in traffic. No cooling problems.

Scott R · Scott R's Garage

Can you post the link for the Griffith's condensor? I have two other people that might be interested in that, both are running hot.

arnebret · 08-13-2002, 12:42 AM

www.griffiths.com, click porsche etc. etc. Pretty damn hard url that one

AFJuvat · 08-13-2002, 07:11 AM

Quote:

Originally posted by Scott R
Secondly you have an AC system that was built to use mineral oil and R12 refrigerant which takes less pressure to use than R134A. So for me I get terrible vent temps (around 50 deg F) in stop and go traffic in 90 deg weather. With R12 I get around 44~45F.

R134A takes more pressure and has different cooling properties than the original R12 so you get more heat off your condenser which translates to more heat through your radiator. This also means that the compressor is working harder to cool your car...

...So based on a recommendation that I had from this board I removed my R134A conversion and went back to R12. Of course it’s illegal in some places but people still have it sitting around.
...Consider this before you make the jump to 134A

I've been getting vent temps of anywhere from 40 - 47 degrees in mine after I converted to 134A (Live in Central Florida)

That said, I do agree with Scott completely, your AC system is designed for R-12 - you convert to 134 at your own risk. I have had great luck so far, but what motivated me to convert was the high cost of replacing all that was wrong with my system.

AFJuvat

Scott R · Scott R's Garage

Beyond the usual steps including vac'ing the system down for an hour or so did you do anything additonal that would be considered a best pratice for this conversion? I have never seen vent temps that low before from 134A.

Lawrence Coppari · 08-13-2002, 08:03 AM

Where can one buy a decent vacuum pump without spending a fortune?

AFJuvat · 08-13-2002, 08:46 AM

I evaced mine by using some old R-12 hose attached to the intake of my compressor.

AFJuvat

arnebret · 08-13-2002, 02:06 PM

Well from the stories i hear from the PO i doesn't look good. From his story i think i might have a lock-up. Though i will have the compressor checked soon and as i said before, if it's gone, the whole a/c in my car is a goner as well

Scott R · Scott R's Garage

Look around there are plenty of people that do "A/C delets" and still have good equipment. In fact I bought a compressor from a fellow Pelican member for a great price!

Lawrence Coppari · 08-14-2002, 03:13 AM

Your air compressor is a piston type or diaphragm type? Would a diaphragm type do the job? I thought about hooking it up to the intake of an old car of mine.