Seal Material

O-rings and other seals on R-134a systems must be made of a different material than that used on R-12 systems. The seals on R-12 systems are usually a form of nitrile butadiene rubber (NBR), which will not retain R-134a. The new refrigerant permeates right through the seal. R-134a systems use "Rubber in Behalf of R-134a (RBR)", which seals in the new refrigerant effectively. R-134a compatible O-rings are typically dark green in color.

The method of sealing has also been changed. The fittings on R-134a systems are generally different. This prevents incompatible parts from being used as replacements in a R-134a system.

Since the seals are still the same size, always verify the use of correct seals when performing service. R-12 type seals used in R-134a systems will allow refrigerant to escape. BMW has made seals available that are compatible with BOTH R-12 and R-134a. Refer to current Parts Microfiche.