Some people say that you require new O-rings that are compatible with the R134a Gas.

I got told that the old seals will get eaten up as they are not compatible with the New gas. Is this true?

Somebody else also said that you have to even change hoses, is this true?

Some websites say that the TXV Valve has to be changed, is this true?

Thanks.

when yo change from r12 to r134 you need to replace somethings in order the system works properly. the seals used for r134 are stronger, the green ones are the ones used for r134, also you will need to flush all the system and check for hoses, if there is any crack or something wrong with one of the hoses you should change it. because r12 and r134 are NOT compatible, you need to replace the valve, dryer, and the oil from the compressor. the reason you need to replace the seals is because the working pressure of r134 is higher than the working pressure of the r12. the green o rings are much stronger than the black ones, commonly used on r12 system. but i have used normal o rings, or seal on r134 an they have worked just great. it just recommended that you use the right seals. good luck

Thanks, So it's the case that there are higher working pressures and the seals need to be stronger to make a better seal. But the old seals wont be "eaten up" as people say?

As for TXV Valves, I'm wondering why they have to be changed when retrofitting to R134a as hardly any of the places do it. Wouldn't the TXV Valve still meter gas into the evaporator regardless of which gas is used?

Thankyou.

the txv valve is designed to work with a specific refrigerant and a specific pressure. also the old valve will have residues from the old refrigerant and oil. you may clean it but I strongly recommend that you replace it with a new one.
and talking about the seal, it may be needed to change some of high side o rings, the ones near the condenser and the one on the compressor, just to make sure the heat wont mess up the old o rings.

Hi,

You mentioned that the working pressures of R134a are higher than R12. Somebody on a forum mentioned that working temperatures are only about 10 PSI Higher on R134a, is that true or is it higher?

Roughly what are the working temperatures of both gasses in PSI? High/Low side?

Thanks.

the working pressures are close to each other, but when the day is hot or there is something wrong with the a/c system, the r134a is more likely to reach higher temperatures that the r12. the r134 low pressure is around 32-34 psi, and high is around 150 - 200 psi, the r12 low side is around 30 psi and high side 140 - 170 psi.