AC Compressor and Pressure Switch (Page 1/1) altownsend OCT 06, 11:36 PM 1986 Fiero, 2.8 V-6, 4-speed manual: I repaired the non-working A/C and tested it after doing the R12 to R134a conversion. I noticed that the system is slightly over-charged. The following is what I am faced with (October 6, 2020) When the AC system is turned on, engine running, setting at 'Normal", the compressor does not activate. I jumped the pins at the receiver/driver with the engine running and ac selected, and the compressor does not activate. I ran a voltage at the pins on the pressure switch and got 10.75 volts. Is this normal? I rant 112VDC directly to the compressor wire, and the compressor spins under power with the engine running, and I get cold AC at the vents. Based on normal settings that should make the compressor run are not getting the compressor activated. But, jumping it with 12VDc, it runs fine, normal engine RPM, cold AC, engine runs at normal operating temperature. Can anyone give me ideas of what I need to check/repair, to get the AC system working as expected. Thanks altownsend OCT 07, 05:46 AM 1986 Fiero, 2.8 V-6, 4-speed manual: I repaired the non-working A/C and tested it after doing the R12 to R134a conversion. I noticed that the system is slightly over-charged. The following is what I am faced with (October 6, 2020) When the AC system is turned on, engine running, setting at 'Normal", the compressor does not activate. I jumped the pressure switch - pins at the receiver/driver with the engine running and ac selected, and the compressor does not activate. I ran 12 VDC check - voltage at the pins on the pressure switch and got 10.75 volts. Is this normal? I ran 12VDC directly to the compressor wire, at the compressor electrical line, with the engine running, and the compressor clutch spins under power with the engine running, and I get cold AC at the vents. Based on normal settings that should make the compressor run are not getting the compressor activated. But, jumping it with 12VDC, it runs fine, normal engine RPM, cold AC, engine runs at normal operating temperature. Can anyone give me ideas of what I need to check/repair, to get the AC system working as expected/designed (when AC turned on with engine running, all systems, including the compressor clutch operate to generate cold air in the cabin)? Thanks