Q: High pressure side of A/C is low (30 psi)

asked by on November 07, 2016

The air compressor low side is at its normal psi. It kicks the compressor on and off between 26 and 30 psi. The high side does not move and it is at 30psi. It should be at 220psi. There are brand new expansion valves so those have been factored out as the problem. The condensor works properly. There is also brand new low pressure and high pressure switchs. Also a brand new trinary switch. All are in working order. What could possibly be making the high side such a low psi? We also charged the system anywhere between 3lbs and 6lbs. That has done nothing to the pressures at all.

Hi there. It sounds like the AC compressor internal valve or the compressor itself has failed and is allowing refrigerant to sit freely and preventing pressure from accumulating; no suction and no discharge equals same pressure on both sides. You could also have a failed ac clutch or relay not engaging the compressor. I strongly suggest asking a qualified technician to perform an inspection to avoid replacing unnecessary parts. YourMechanic has several technicians available who can assist you with an AC does not work inspection.

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