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Joined: Sun Jan 14th, 2018
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1) The A/C is inoperative/does not operate correctly. Possible causes; fuse, A/C control relay, circuit open/short, A/C cycling switch, A/C system discharged/low charge, pressure cutoff switch, or function selector switch.
2) Insufficient A/C cooling. Possible causes; restricted A/C evaporator core orifice, restricted A/C evaporator core, low refrigerant level, A/C cycling switch, temperature blend door actuator control, engine overheating, condenser airflow restricted, or heater control valve.
Electrical diagram for A/C compressor clutch:
Clutch Cycling Orifice Tube Type Refrigerant System
All A/C systems leak at the compressor pulley, this keeps the bearing lubricated. The only way to know if the system has the correct charge is to empty the system, pull vacuum, and then recharge.
The "Heater Valve" is a vacuum operated valve on the heater core outlet hose. This controls flow of engine coolant through the heater core. Opens when heat is selected, closes when cool is selected.
Hopefully some of this is helpful.