HVAC CONTROL HEAD INOPERATIVE NO DISPLAY

SUBJECT: HVAC CONTROL HEAD INOPERATIVE - NO DISPLAY (RECYCLE IGNITION SWITCH/RECONNECT BATTERY)

VEHICLES AFFECTED: 1990-93 "C/K" AND TOPKICK/KODIAK

CONDITION:

--------- The HVAC control head on some 1990-93 model year C/K and TopKick/Kodiak models may not illuminate when the vehicle is first started. This condition is much more likely to occur after a battery disconnect or control head replacement but may occur after any ignition cycle.

CAUSE:

----- The condition is not permanent, it stems from the control head not receiving a correct signal when the ignition is turned on.

CORRECTION:

---------- Recycling the ignition switch may bring the control head back to normal operation. If cycling the ignition does not work, disconnect and reconnect the battery making sure that a good electrical connection is maintained when reconnecting (avoid "chattering" the battery line).

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.