HVAC TEMPERATURE UNEVEN NEW REVISED SERVICE PROCEDURE

SUBJECT: DRIVER/PASSENGER HVAC TEMPERATURE UNEVEN (NEW SERVICE PROCEDURE)

VEHICLES AFFECTED: 1991 PARK AVENUE/PARK AVENUE ULTRA 'C' MODEL

CONDITION:

---------- Improperly adjusted HVAC temperature doors on some 1991 Park Avenue/ Park Avenue Ultras may result in HVAC outlet temperatures being noticeably different from side to side. Adjusting the passenger side temperature control may not be enough to balance the system.

CORRECTION:

----------- Adjust both temperature doors using the following procedure:

1. Start vehicle. Set the control head on maximum heat 90 degrees (32 degrees C).

2. Set the passenger climate control to full warm.

3. If the ambient temperature is above 90 degrees (32 degrees C), disconnect the in-car temperature sensor.

4. Allow 45 seconds for the HVAC programmer output cranks to move to the full warm position.

5. Unsnap the driver air mix valve link from the threaded rod. Gently pull the driver air mix valve crank towards programmer until valve seats. (See illustration)

6. Pull the threaded rod toward the programmer until it hits the stop. Push the threaded portion of the link into the slot on the plastic pin on the driver air mix valve crank.

7. Unsnap the passenger air mix valve link from the valve crank. Gently pull the passenger air mix valve link toward the programmer until the valve seats.

8. Pull the passenger air mix valve crank toward the programmer until it hits the stop.

9. Snap the passenger air mix valve link onto the valve crank.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.