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Conversion to 134A

HowardRT on Sat July 02, 2011 10:32 AM User is offline

Year: 1983
Make: Mercedes
Model: 240D

I am about to convert my 240D MB to 134A. I will install a new R-4 compressor, receiver/dryer, expansion valves, etc. and will flush the system. Does anyone know if the compressor will come filled with ester oil or PAG? I understand that residual R12 could break down the PAG oil. I also read in the MB manual that, when installing a new compressor in a system that has been flushed, I shouldn't add any oil since the compressor has the right amount. Is this correct? Any comments on this would be appreciated.


bohica2xo on Sat July 02, 2011 4:46 PM User is offline

Don't expect great performance from a conversion on that vehicle. If you must convert it, make sure the fans are working properly, and you might consider upgrading the condensor as well.

As for the compressor carrying the proper oil charge - that may have been correct in 1994 if you bought the compressor directly from the MB parts counter. Do not count on a compressor having any oil in it. It may have a partial charge, or just enough to assemble it. If the compressor has been sitting on the shelf for a couple of years, it may be contaminated with moisture anyway...

You should decide on an oil type - either an Ester like BVA 100, or a DEC PAG oil. Avoid SEC PAG oils, they contaminate with moisture far too easily. Once you settle on an oil, buy enough to flush the compressor with, as well as fill the system with a proper oil charge. Flush the new compressor with the oil you will be using in the system, then add the listed oil charge to the system before you close it up & evacuate.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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