Comments of water entering the front or rear passenger compartment on either side, may be caused by a restriction of the air conditioning evaporator drainage tray check valve. The rubber check valve can be seen protruding through the cowl, near the evaporator's freon lines under the hood. Additional checks should also be made to insure that the evaporator case has the proper sealing along the dash cowl area.
If this valve becomes obstructed, restricted or "sticks" closed, the drain off water from the evaporator core is allowed to fill up inside the evaporator case and eventually overflow into the passenger compartment.
If this condition is suspected, take the necessary steps to improve the check valve's flow.
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.