CAK_ Comm. Error Auto Multi-Zone D (Advisory)
To avoid serious injury follow all warnings and instructions in the manual. Wear appropriate personal protective equipment.
| Cause | Solution |
| No AC power to the AMZ | Verify the AMZ MZLP4 is turned on by confirming the disconnect switch on the heat box is in the ON position. |
| AC disconnected switch broken | Disconnect the AMZ MZLP4 from AC power. Check wiring to the switch. If wiring is good, replace the AC disconnect switch of the heat box. |
| Faulty AMZ MZLP4 control board | Replace AMZ MZLP4 control board. |