Decelerator or Hand Throttle (STD cab) Position potentiometer voltage is too high
Mid range clutch is not calibrated
Aux 3rd Lower Coil solenoid shorted to 12 volts.
Low pressure switch (+) input shorted to ground
Foot Throttle Position potentiometer voltage is too high (engine controller pin B30)
Mid range clutch is not calibrated
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.