Engine Speed Sensor (8.3, 9 Liter) or Cam Sensor (15 Liter) is failed
Odd clutch solenoid coil or its wiring shorted to power
Aux 4th remote valve FLOW potentiometer is failed in the Armrest Controller
Evaporator sensor open or shorted to power
Engine Speed Sensor signal is failed (no signal at engine controller pin A17)
Odd clutch solenoid coil or its wiring shorted to power
Partial frosting and sweating of lines combined with poor cooling, fan belt slipping, loss of refrigerant, restricted or clogged liquid line or expansion valve malfunctioning.