The crankshaft seal is bathed in lubricating oil at a pressure equal to the suction pressure of the refrigerant. The first indication of crankshaft seal failure is excessive oil leaking at the shaft. When the seal must be replaced or when it shows signs of abnormal wear or damage to the running surfaces, a definite reason can be found for the abnormal conditions. Make an inspection to locate and correct the trouble, or the failure will recur. Seal failure is very often caused by faulty lubrication, usually because of the condition of the crankcase oil.
Dirt frequently enters the system at the time of installation.
After a period of operation, foreign material will accumulate in the compressor crankcase, tending to concentrate in the oil chamber surrounding the shaft seal. When the oil contains grit, it is only a matter of time until the highly finished running faces become damaged, causing failure of the shaft seal. Oil in this condition will not provide satisfactory lubrication and will cause failure of the compressor parts. Use a refrigerant dehydrator when the compressor is put into operation if you suspect that moisture may be a problem. If the seal is broken to the extent that it permits excessive oil leakage, do NOT attempt to pump the refrigerant out of the compressor.