R134a and R12 Seals, difference?

[Z2TT]

Hello,

I've contacted many A/C Places about retrofitting to R134a and most say that a new reciever/drier has to be installed, system flushed and compatible oil used.

Some articles I have read online say that the new gas (R134a) will eat up the current seals as they are not compatible. Is this correct?

Thanks.

[Quality]

I have done quite a few retrofits from r12 to r134a and had to make sure that any seals such as o rings etc were changed to ensure they were made of neoprene.

[Z2TT]

Are neoprene seals a requirement for R134a retrofit? as in is the gas not compatible with other types of rings?
Will it degrade them or eat them up so to say.

Thanks.

[Quality]

What I do know is that neoprene is suitable for continuous duty with r134a so if you know that it is neoprene as opposed to not knowing at least you can be certain.

[Z2TT]

As for Compressor Seals, do they need to be replaced in most cases?

Somebody mentioned to me even the actual HOSES need to be changed, is this true?

[Quality]

It depends what the hoses are made, its quite possible they may need changing. as for the compressor it would probably be better to contact the comp manufacturer

[vtmpnate]

Hi Z2TT. Materials for R-12 o-rings are made to work with mineral oil and may react negatively to PAG and POE oils by swelling up and deteriorating rapidly. I also understand (but I may be wrong so please correct me if I am) that the R12 molecule is larger than the R134a molecule, such that a compressor shaft seal that worked with R12 may not necessarily work with R134a. I've also heard that used R12 hoses heavily saturated with oil may still work with R134a. R134a have an added nylon barrier layer in them that prevents the gas from otherwise leaking out.

[freezerguy69]

I'm not a fan of R134.. R12 molecule is larger, lower pressure, better cooling capability, works better in higher temps, etc.

At least from my experience.

That was slightly off subject. The seals are different. Your local parts store that carries AC supplies should have the proper seals. replacing the seals isn't needed I've gotten away with just new dryer and filling with R134 but to do the job correctly new proper seals will benefit greatly.

I feel the coffee kicking in, sorry for the rant.

[Z2TT]

Thanks everyone.

A few more questions if you people don't mind.

I don't quite understand the need for the nylon barrier. The rubber hoses I have on my R12 car are very thick, how could the gas leak past a 6mm thick rubber wall? Why is there a need for the nylon layer inside? Excuse my ignorance but that is how I understand it, that there is a nylon barrier on the inside of the hose.

Can somebody else please confirm that PAG oil can swell up the R12 O-rings? Other people tell me that it wont swell them up or eat them up, just that Neoprene seals can withstand higher pressures from R134a, But this is the first time i've heard of the swelling cause by PAG oil, but I'd like to know more about it as I'm interested.

Also, some cars that I have had would turn on the a/c whenever I put the car into reverse, I'd assume this is to cycle the A/C System to prevent things from drying up or siezing? I'd like to know what exactly can be damaged if the a/c system is not used for a long time. A mechanic told me that O-Rings will dry up from lack of lubrication, where as one of the Staff from HECAT mentioned that Static seals such as o-rings would not be affected by extended periods of non-use, but Compressor shaft seals will.

So i'd like to know if O-Rings are affected by not using the a/c for a long time, how about the thin rubber seals on EPR Valves?

Thanks everyone.

[Z2TT]

Hi,

From the replies I have been thought that R134a when used with PAG/POE oil is more likely to cause leakages when used with the old O-Rings, I believe these are the NBR (Nitrile Rubber) Ones.

However I have read this following post on O-rings :

http://www.autoacforum.com/messageview.cfm?catid=20&threadid=8612

It seems to contradict what has been said here.

"The switch to HNBR is really only for heat resistance, and maybe a little abrasion resistance for the Ford springlock couplers; it is not a chemical compatibility issue."

"Compatibility of NBR O-Rings is classed as good with R12, R134a, Mineral oil, POE oil, and PAG oil. The temp range for NBR is -22F to 210F."

From what I have read on that post the switch to HNBR is not needed in R134a, and that NBR works fine with both gasses, so I'm not sure what to believe.