There have been some customer comments of no medium blower speed on standard heater (C-41) equipped vehicles. The blower functions normally on high speed but there is no apparent difference in air flow between low and medium speed.
The 51 circuit and the 52 circuit wires at the blower motor resistor, cavities D and B, are reversed.
Refer to service manual 8A-60-0 for proper wiring procedure.
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.