A/C Evaporator Freezing - kw A/C air charge control duct HVAC low passenger performance side temperature

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

A/C Evaporator Freezing

VDOT Description and Operation:

The Variable Displacement Orifice Tube (VDOT) refrigeration system has a variable rate compressor. The compressor can match the automotive air conditioning demand under any conditions without cycling. The basic compressor mechanism is a variable angle wobble-plate with axially oriented cylinders. A bellows actuated control valve controls the compressor displacement. This control valve is located in the rear head of the compressor that senses the suction pressure of the compressor. The crankcase suction pressure differential controls the wobble-plate angle which adjusts the compressor displacement.

If the evaporator is freezing and all other possibilities have been eliminated, suspect the control valve assembly in the compressor. If the control valve sticks, it could cause the compressor to have maximum output all the time causing the evaporator to freeze. On some compressors the control valve is serviced separately.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(2000 - 2005 Buick Century) and (2000 - 2004 Buick Regal) and (2000 - 2001 Chevrolet Lumina) and (2000 - 2005 Chevrolet Monte Carlo/Impala) and (2000 - 2002 Oldsmobile Intrigue) and (2000 - 2005 Pontiac Grand Prix)

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