A condition may exist on some 1985 and 1986 M vans with rear A/C (air conditioning) and/or rear heater where low and medium blower speeds both operate as low speed. This may be due to incorrect positioning of the wires at the rear blower motor resistor connectors. The 1985 and 1986 wiring diagrams are also incorrect.
The proper locations for wires at the resistor connectors are shown in Figures No. 1 and No. 2. The procedure for relocating wires is shown in Figure No. 3.
With connector plugged into resistor, correct wiring position is shown looking at connection from top.
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.