New control assemblies went into production on July 11, 1984 with logic changes to assist heater and A/C performance. The following changes are incorporated in the new unit:
1. Remember blower setting if mode is changed.
2. Remember mode and blower setting for approximately 30 minutes after ignition is turned off. Approximately 30 minutes after shut down, the system will revert to auto mode/auto fan.
3. Revise blower curve so blower comes off "hi" blower sooner in heater mode.
4. Change time for temperature display to change one degree in approximately 1/2 second. Previous display change took approximately one second.
5. Changed LED indicators showing mode and blower settings to lower intensity.
Service remanufactured units with these changes can be obtained from GWDD under part numbers:
1227047 with rear defogger option (C49) 1227048 without rear defogger option
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.