How to determine if the air conditioner compressor needs to add refrigerating oil

It is improper to add refrigeration oil arbitrarily based on experience. Four signs help confirm oil replenishment. First, abnormal knocking noise from the compressor due to insufficient lubrication. Second, low oil level below the minimum scale on the compressor sight glass after shutdown. Third, poor cooling performance and frequent high-temperature protection, caused by poor heat dissipation from oil shortage. Fourth, previous refrigerant leakage, compressor overhaul or pipeline replacement, as leaked refrigerant always takes away lubricant. Never top up oil with over-high oil level to avoid oil slugging and valve damage. Add specified-grade refrigeration oil quantitatively only when the oil level is low with abnormal faults, in line with the manufacturer’s standard oil level.