Mitsubishi Electric PUHY-HP144TSHMU-A Service Handbook page 159

[ IX Troubleshooting ]
1. Error Code
6600
Address overlap
2. Error definition and error detection method
An error in which signals from more than one indoor units with the same address are received
The address and attribute that appear on the remote controller indicate the controller that detected the error.
3. Cause, check method and remedy
Two or more of the following have the same address:
Outdoor units, indoor units, LOSSNAY units, control-
lers such as M-NET remote controllers.
<Example>
6600 "01" appears on the remote controller
Unit #01 detected the error.
Two or more units in the system have 01 as their ad-
dress.
HWE0716A
Cause
- 150 -
Check method and remedy
Find the unit that has the same address as that of the
error source.
Once the unit is found, correct the address. Then,
turn off the outdoor units, indoor units, and LOSS-
NAY units, keep them all turned off for at least five
minutes, and turn them back on.
GB