Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 255

[ IX Troubleshooting ]
Error
Error definition and error detec-
Code tion method
6608 No response
When no response command
is returned although acknowl-
edgement (ACK) is received
after transmission, an error is
detected.When the data is
transmitted 10 times in a row
with 3 seconds interval, an er-
ror is detected on the transmis-
sion side.
Note: The address/attribute
appeared on the display
on the remote controller
indicates the controller
where an error oc-
curred.
Cause
(1) The transmission line work of
one of the indoor unit, heat
source unit, or the BC controller
is performed while the power is
on, the transmitted data will col-
lide, and the wave shape will be
changed.
(2) The transmission is sent and re-
ceived repeatedly due to noise.
(3) The transmission line voltage/
signal is decreased due to erro-
neous sizing of transmission
line.
Farthest:
200 m [656ft] or less
Remote controller wiring:}
10m [32ft] or less
(4) The transmission line voltage/
signal is decreased due to erro-
neous sizing of transmission
line.
Wire diameter:
2
1.25mm [AGW16] or less
- 246 -
Check method and remedy
1) When an error occurs at commission-
ing
Turn off the power sources of the heat
source unit, indoor unit, BC controller,
and LOSSNAY for 5 or more minutes,
and turn them on again.
-> When they return to normal opera-
tion, the cause of the error is the
transmission line work performed
with the power on.
If an error occurs again, check 2).
2) Check (3) and (4) on the left.
-> If the cause is found, correct it.
-> If no cause is found, check 3).
3) Check transmission wave shape/
noise on trans-mission line by follow-
ing <Investigation method of transmis-
sion wave shape/noise>.
Noise is the most possible cause of
the error "6602".