Climate Control Troubleshooting

[ctaylor738]

I recently installed a ProgRama rebuilt ACC control (push button) unit in my 560SL. It came with an instruction sheet that had some simple troublshooting steps that may help isolate problems.

All steps are performed with the control unit removed so that the 12 pin connectors on each side can be accessed. "L" means left connector, "R" means right side.

1. Set meter to amps. Ignition on. L 12 to L 10 < 1.3 amps. If higher, replace aux water pump BEFORE installing new control unit.

2. Meter to ohms. Ignition off. L 12 to R 4 = 11 to 19 ohms. If not, replace monovalve.

3. Same, R 6 to R 3 > 35 ohms. If not replace AC compressor relay.

4. Same, R 6 to R 3 > 55 ohms. Check ETR switch, check refrigerant pressure.