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O rings, R12 and mineral oil

br1anstorm on Tue August 26, 2008 5:52 PM User is offline

Year: 1990
Make: Mercedes Benz
Model: 560 SEC
Engine Size: 5.6 litr
Refrigerant Type: R12
Ambient Temp: 25 deg C
Pressure Low: n/k
Pressure High: n/k
Country of Origin: United Kingdom

My Euro-spec Merc has a leak at the expansion valve, so we are planning to replace both the expansion valve and also the receiver/drier, then recharge the system. We will presumably need to check/top-up the mineral oil too. Can anyone advise on whether special 'O' rings are needed for an R12/mineral oil system? I notice that many O ring kits are labelled as use-able on both R12 and R134a systems. But I'm not clear what the difference is between HNBR and Neoprene rings, for example, or between the black ones and the green ones. Is there a simpel explanatory guide anywhere on the 'net which I can study? I guess I'll have to try and source new O rings here in the UK, but I need to be clear about exactly what type of O rings my system needs.

By the way I also have a 1993 US-spec Jeep Cherokee and a 1988 Pontiac Fiero - both with R12 systems too. So the O ring question will arise for them too in due course.


TRB on Wed August 27, 2008 12:04 AM User is offlineView users profile

Both HNBR and Neoprene will work with R12 and mineral oil.


When considering your next auto A/C purchase, please consider the site that supports you:

retrofit on Wed August 27, 2008 12:25 AM User is offline

More o-ring info here and here. Fiero specific A/C info is located here.

Edited: Wed August 27, 2008 at 12:59 AM by retrofit

br1anstorm on Wed August 27, 2008 5:35 PM User is offline

A huge thank you to Retrofit for those links and that info. The Santech site has a wealth of useful factual and technical detail. And the link to the Fiero Sparks website was an unexpected but very welcome bonus. Much appreciated!


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