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R12 to R134a - Seals Compatible?

Z2TT on Wed November 04, 2009 1:54 AM User is offline


Talking in General, is there a difference between seals (o-rings) and compressor seals used in R12 and R134a Systems.
Some people seem to say that If you dont change the o-rings, the R134a gas will eat up the seals and leak. Is this True?

Somebody else who does A/C Re-gassing told me even all the Hoses need to be changed. Is this true aswell?


Chick on Wed November 04, 2009 3:31 PM User is offlineView users profile

Yes, O rings are a different material, and hoses use barrier type hose for r134a due to the smaller molecule being able to leak out of the R12 hoses, although in most cases it's minimal..Any time you open the system use new O rings, HBRN type are suitable for both R12 and R134a.. those are the green ones...

Email: Chick


Freedoms just another word for nothing left to lose

Z2TT on Fri November 13, 2009 1:48 AM User is offline

Thanks Chick,

So does the R134a actually leak out through the rubber wall on the hose? Would you be able to shine a UV light on the outer rubber wall and notice a leak?

What about TXV Valves and EPR Valves? Do they need to be changed for R134a and why?

As for EPR Valves, Wouldn't you need a different spring setting? Because how I see it the EPR Valve has a spring that resists gas flow after the evaporator to
maintain a certain pressure in the evaporator, and I believe the spring in the EPR valve is rated at a certain pressure, now if you change gasses from R12 to R134a
Would you need a different EPR Valve because the R134a gas has different properties as in at what temperature it is liquid state and what temperature it is gas state.
I read that the Function of the EPR valve is not to let the pressure drop to low in the evaporator so refrigerant does not enter the compressor at a liquid state.


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