Dear Friends:
For the first time I completed this Sunday to flush the whole AC system from my 1982 300SD. As I also found leakage in the compressor body I had it replaced for a new (not rebuilt) compressor. With the system completely clean I installed new expansion valve, new receiver and all new O-rings and finally vacuumed and checked for leakage of vacuum and no leaks showed in the vacuum gauge. After everything in place I started to add new oil in the following way:
The compressor came with an amount of oil, which I don't know how much.
I then added 6 Fluid OZ in the suction line considering that the whole system was evacuated and was completely empty. After oil added into the system I started to add new 134a as following: Connecting the high and low pressure gauges I used the 12 Fluid OZ can until the clutch engaged. From there I added one more can with attention in the pressure and the sight glass in the receiver for bubbles. When second can was empty, the low pressure gauge was showing 55 PSI and the high gauge was showing 300 PSI. The ambient temperature at that time was around 88 F.
With the engine running around 2000 RPM the new compressor got hot and with a grinding noise but I let it run for about 25 to 35 minutes only.
The condenser cooling fan kicked on and stay on for the same length of the time as the engine in my garage.
Today I just try to run when coming back from work but as I was not sure about the quantity of oil and refrigerant added to the system and with the compressor noise present, I turned it off and decided to get help from people in this site that knows better about Mercedes AC.
The system is cooling the air but not much as any other car. In other words, it is just cooling the air but not bringing it to a cold as a good AC system.
Please give me your help regarding oil and refrigerant quantities and also about the high and low pressure in the gauges. About compressor noise also will be helpful to know.
Thanks everyone.

Nyko46

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Nyck - TX - USA