A/C CONTROL HEAD FAILURE (REPLACE ACTUATOR AND HEAD)

VEHICLES AFFECTED: 1980-84 C, 1980-85 El 1980-85 B, 1980-84 B-C WAGONS

Automatic Air Conditioning systems (C-68) can have a failing mode actuator that can cause a control head failure. This is caused when the current required to operate the motor in the actuator exceeds the current handling capability of the control head. Should a vehicle come in with the mode LED's flashing in the control head, the following procedure must be used:

SERVICE PROCEDURE:

1. With the key off, remove the control head from the vehicle.

2. Using a suitable jumper wire, apply 12 volts to pin C of 22 pin connector which is the control side of each actuator or the power output of the 22 pin control head connector (pin C of actuator).

3. Using a Kent-Moore digital volt-OHM meter J 34029-A, or equivalent, set to the 2-amp scale, connect one lead to a suitable ground.

4. Connect the other lead to the drive side of each actuator motor, pin A and check the current draw. This can be done at the 22 pin connector. If the motor does not operate, check the fuse in the meter.

5. If at any time the current draw of any actuator exceeds 2.0 amps, replace the actuator motor and control head at the same time.

NOTICE: Connecting a new control head to a defective actuator will damage the new control head.

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.