GM Service Manual Online
For 1990-2009 cars only

If the Function Test or other diagnosis indicates improper air delivery or a failure in the shifting of modes when moving the mode rotary knob. Inspect the attachment of the affected control cable at the heater module.

  1. Ensure that the cable loop connects to the actuator.
  2. Ensure that the cable sheath is retained.
  3. Remove the instrument panel storage compartment.
  4. Observe the action of the control cable.

If the cause of the condition is not discovered, disconnect the control cable at the valve.

Inspect the system for the following items:

    • Improper air control valve travel and effort
    • Improper control cable travel at the heater module end while moving the mode rotary knob is moving.
    • If the cable does not move, inspect for a broken cable or control assembly part.
    • An unattached cable end at the control assembly
    • A sharp kink in the control cable sheath that may cause severe binding.