Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 252

(3) System connected to the system controllers (MELANS)
Error Code
6607 No ACK abnormality
(Contin-
ued)
Error
Error dis- Detection
source ad-
play
dress
M-NET re- M-NET re- No ac-
mote con- mote con- knowl-
troller troller (RC) edgement
failure (RC) System (ACK) at IC
controller transmis-
(SC) sion to RC
system No ac-
controller knowl-
(SC) edgement
(ACK) at
MELANS
transmis-
sion to RC
Error definition and error detection method
The error is detected when no acknowledgement (ACK signal) is received after the
transmission. (eg. When the data is transmitted six times in a row with 30 seconds
interval, the error is detected on the transmission side.)
Note: The address/attribute appeared on the display on the remote controller
indicates the controller which did not provide the response (ACK).
Cause
method
Same as grouping of units in a sys-
tem with multiple heat source units
1. Error occurrence on some IC
(1) Same cause as that for system
with one heat source unit
2. Error occurrence on all IC in the
system with one heat source unit
(1) An error is found by the heat
source unit.
Total capacity error (7100)
Capacity code error (7101)
Error in the number of connect-
ed units (7102)
Address setting error (7105)
(2) Disconnection or short circuit of
the transmission line for the heat
source unit on the terminal block
for centralized control line con-
nection (TB7)
(3) Turn off the power source of the
heat source unit.
(4) Malfunction of electrical system
for the heat source unit
3. Error occurrence on all IC
(1) Same causes as (1) - (4) de-
scribed in 2.
(2) The male power supply connec-
tor on the heat source unit is
connected to the female power
supply switch connector (CN40)
for the transmission line for cen-
tralized control.
(3) Disconnection or shutdown of
the power source of the power
supply unit for transmission line
(4) System controller (MELANS)
malfunction
- 243 -
[ IX Troubleshooting ]
Check method and remedy
Same remedy as that for grouping of units in
a system with multiple heat source units
Same remedy as that for system with one
heat source unit
1) Check the LED display for troubleshoot-
ing on the heat source unit.
->If an error is found, check the check
code definition, and correct the error.
->If no error is found, check 2).
2) Check (2) - (4) on the left.
Check (1) - (4) on the left.