Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook page 266

Error
Error definition and error detec-
Code tion method
6603 Transmission circuit bus-busy
1. Generated error when the
command cannot be trans-
mitted for 4-10 minutes in a
row due to bus-busy
2. Generated error when the
command cannot be trans-
mitted to the transmission
line for 4-10 minutes in a
row due to noise
Note: The address/attribute
appeared on the display
on the remote controller
indicates the controller
where an error oc-
curred.
6606 Communication error with the
transmission processor
Communication error between
the main microcomputer on the
indoor unit board and the mi-
crocomputer for transmission
Note: The address/attribute
appeared on the display
on the remote controller
indicates the controller
where an error oc-
curred.
Cause
(1) The transmission processor
cannot be transmitted as the
short-wavelength voltage like
noise exists consecutively on
the transmission line.
(2) Error source controller failure
(1) Data is not properly transmitted
due to accidental erroneous op-
eration of the controller of the er-
ror source.
(2) Error source controller failure
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[ IX Troubleshooting ]
Check method and remedy
No noise indicates that the error source
controller is a failure.
If noise exists, investigate the noise.
-> No noise indicates that the error
source controller is a failure.
-> If noise exists, investigate the noise.
Turn off the power source of the outdoor
and the indoor units.(When the power
source is turned off separately, the micro-
computer will not be reset, and the error
will not be corrected.)
-> If the same error occurs, the error
source controller is a failure.