AC is not blowing as cold as it used to and makes a knocking noise when the AC is on. The low side is higher then the high side in pressure. Low pressure is 87 and high pressure is 55. I took the AC compressor off and spun it and it seemed like it was working. Freon level is good. I was leaning towards the ac compressor control solenoid valve. Any help would be greatly appreciated, thank you!