5ks A/C oil charge?

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Bob and all,

I have just done this on my 87' 5000cs TQ. I replaced the compressor, 
accumulator and every O-ring on the car. I flushed the system in individual sections 
and then looked for an oil capacity. Bentley has no mention of it. I have the 
factory service training manuals for the 5000 climate control, troubleshooting 
ad repair. In an exploded view of the compressor and magnetic clutch 
assembly, there is a note that states: NOTE, Replacement compressors are filled with 
320 ml (10.8oz.) of refrigerant oil. Before installation of new compressor, 
flush system. I read this as the system takes 10.8oz. and if you don't flush the 
system, the system will then be over serviced with refrigerant oil. NEVER, 
EVER flush the receiver dryer or accumulator. The desiccant bag can/will be 
damaged. It acts as a drying agent.

I have been hearing a lot of different people stating a lot of deferent 
theories about converting to R-134A. I've heard about using Freeze12 or Auto12 as a 
direct replacement for R12. My opinion only, but I will keep my R12 system 
R12 until I can't find it anymore. I've owned my 87' 5000cs TQ for a while now 
and I have never had to mess with the A/C. You could hang meat in my car on a 
100 deg. day. But 282,000 miles and probably the same on the compressor when if 
failed forced me to perform A/C maintenance. I've talked to guys who swear 
that R-134A works great in an R12 system and others who state that Freeze/Auto12 
works just as good as R12.

When changing from R12 to R-134A, your switching to a refrigerant that is 
intended to be used at a lower pressure than R12. Also, the expansion 
valve/orifice tube/restrictor (whatever term you want to use) is calibrated for R12, not 
R-134A. If you do switch, you should only use 80-85% of the total capacity of 
the original R12 charge. So you are then running less refrigerant in a system 
that was intended to run at higher pressures. There are pros and cons to 
everything, if the system is sealed and operating correctly, it should give you 
trouble free cooling for many years. If not, then something is wrong.


Jim Furdyn
1983 UrQuattro #170 
1987 4000cs Q
1987 Euro 200/5000cs TQ 282,000 miles
1996 A6 Quattro Avant 
1987 Mercedes Benz Truck model 1219