Chiller coldroom compressor problems.

[Lucas]

I've got a problem with a small integral chiller c/r compressor. The compressor is an Aspera NE 7213E (R22). The c/r is approx 7ft square (Trimco me thinks). The problem is the compressor is overheating and cutting out on o/load. Condensor clean and condensor motor running ok.

When running the compressor body is very hot.

Its got me confused because once compressor cools and then runs it brings c/r temp down, cycles on stat cutting in and out quite happily, yet a few days later cuts out on o/load again?

Comp valve or overcharged maybe?

I think I'm going to remove gas, check comp and if that is ok, flush system, replace drier, vac out and re-gas to see if that works.

There is no ID label so I'm not sure quantity of R22 to put in. I don't want to overcharge/ undecharge system. The system uses capillary tube. Any suggestions on back pressure I should be looking at and how critical is the charge in a capillary system? At moment unit running around 40psi.
Thanks
Lucas.