Automatic Climate Control (ACC)

In order to avoid damage to the electronic circuits in the Automatic Climate Control (ACC) control module, take the following action:
- Whenever working on the ACC unit, always detach the negative battery lead.
- When arc welding, detach the negative battery cable and the regulator connection and unplug the 25-pin connector from the climate control module.
- When taking readings and diagnosing faults, the 25-pin connector for the climate control module should be detached.
- M1988 and later:

The heat sink on the ventilation fan speed control is live (+12V) when the ignition is on. If the heat sink is grounded, the speed control is destroyed.

When conducting fault diagnosis (AUTO and VENT pressed simultaneously), the climate control module runs a program. The display then shows the number of faults and gives a diagnostic trouble code for each one.