Some customer comments have been received concerning windshield condensation only during periods of high humidity and high heat.
This condition may be caused by air conditioning cold air leakage through voids and cracks in the upper panel of the defroster duct. These voids and cracks have been sealed on vehicles starting with 1988 production.
This condition can be improved on vehicles prior to 1988 production by using either thumb grade sealer, strip caulk, body sealer and/or duct tape to seal any and all voids and cracks in the upper panel of the defroster duct.
Use existing labor operations and time.
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.