The R4 compressors are known to fail. When I had my w123, I bought a Hancock Industries brand new R4. New drier and expansion valve as well. Did a full system flush as well. Used the 134a refrigerant and BG FridgiQuite oil. Noticed in city traffic, the compressor would stop turning, but the clutch stayed engaged, burning the clutch and the bearing. Replaced those, then swapped out the 134a for Duracool. Big difference. Less head pressure. That ended the problem I had. It also had cooler air out of the vents.

Now, if you are going to use Rollguy's Sanden set up and get a parallel flow condenser, stay with the 134.

Duracool works well for me. I even run it in my w124. YMMV.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D