I only checked the low side. When I go back, I'll tap the high side and check the pressure. If there's air in the system, I should see higher than normal high side pressure. If it has lower than normal pressure like the low side, there's probably very little or no air in the system. Then, I'll decide if I should replace the compressor or not. I can get a generic equivalent compressor for half the cost of the Subzero compressor.