If the compressor efficiency is unreasonably high, it is because errors in the measurement or if the compressor has an active cooling. Active cooling can be a fan, water or oil cooling or liquid injection. It may also be a result of liquid refrigerant in the suction line of which boils and cools the compressor. For stable operation and without cooling, compressor efficiency for the most efficient compressors have a compressor efficiency of appr. 75%.