Got a call to a catering company, walk in cooler was running at 55 F. System was low on charge (no LP switch), low side was aprox 0 psi, sight glass inside has a brown stain, very hard to see thru. System is R22, Semi H Comp. I found a small leak at High side schrader evacuated to 500 mic and charged, normal pressure, superheat good, cooler holding normal temp 38F. The oil was at bottom of compressor glass I added to just below ctr with MO. Is this brown tint any indication of system failure almost looks like dirty oil caused it or a winding burn out? If so is there any hope should I change or add filters and new oil to prevent more damage.
Thanks for any help