TEMPERATURE CONTROL OR HVAC LEVERS LOOSE (REPL. HOUSING)

SUBJECT: TEMPERATURE CONTROL OR HVAC LEVERS LOOSE OR BINDING

MODEL and YEAR: 1986-92 S/T TRUCKS

Owners of some 1986-92 S/T Trucks equipped with air conditioning may comment on loose or binding temperature control or HVAC mode selection levers. These conditions may be caused by broken housing bosses at the plate mounting screws on the A/C control (Figure 3). The result may be inability to actuate certain HVAC modes or obtain maximum heating or cooling.

Previously it was necessary to replace the complete A/C control assembly to correct this condition. The control assembly included the valves, switches, bezel and lighting.

The housing, P/N 16074394, is now available allowing this condition to be corrected when other parts of the control are operating properly. Partial disassembly of the A/C control is required.

SERVICE PROCEDURE:

1. Remove the A/C control assembly from the instrument panel.

2. Place the Temperature and Mode controls in the upper position.

3. Apply thumb pressure to each of these control knobs to hold them in the upper position while using a small screw driver to pry off the knobs (Figure 1).

4. Use the same procedure to remove the blower switch knob.

5. Disconnect the 2 light sockets from the housing by twisting the sockets counterclockwise.

6. Remove blower motor switch.(Figure 2)

7. Remove the 2 control base plate mounting screws.(Figure 2)

8. Remove the control baseplate.

9. Remove the 4 housing to bezel mounting screws.(Figure 3)

10. Discard the broken housing.

11. Apply a small amount of GM silicone grease, P/N 12345579, or its equivalent to areas of the new housing where the mode and temperature levers protrude through the housing slots.(Figure 3)

NOTE: Do not use petroleum based lubricants. Petroleum based lubricant causes the housing material to become brittle and generate a repeat failure.

12. Reassemble using the reverse procedure. Use care when assembling the base plate to the housing and bezel. The mode control lever must be inserted through the mode indicator.(Fig.3)

13. Torque the housing, baseplate and blower switch mounting screws to 6-10 lbs.in.

14. If necessary, install new knobs on mode, temperature, and blower controls to ensure proper retention.

SERVICE PARTS INFORMATION

PART NUMBER DESCRIPTION QTY ----------- ----------- --- 16074394 Housing, HVAC Control 1 16062663 Knob, Mode and Temperature Control 2 -If necessary 16062650 Knob, Blower Motor Switch 1 -If necessary 12345579 Grease, Silicone

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

LABOR OPERATION DESCRIPTION --------------- ----------- D0362 R & R HVAC control

ADD: Replace housing

Use applicable labor time guide for labor hours.

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.