I just replaced the compressor (a re-man), dryer and expansion valve on my '95 S320. We thoroughly vacuumed the system after cleaning with the proper solvent, recharged to just a bit less than 2.5 pounds of R134.
The problem is that the compressor turns on for about 10 seconds and then off for 2-3 minutes, the starts over for 10 seconds, off 2-3 minutes, etc. All the pressures are within the specified range. The compressor runs good when we hot-wire it directly (although it does not cool more than a 15 degree drop). I replaced the pressure sensor on the dryer and now have no diagnostic errors coming up. The belt tension seems OK, I sprayed some cleaner on the clutch, just in case. Any ideas?