Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 214

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(2) Grouping of units in a system with multiple heat source units
Error Code
6607 No ACK abnormality
(Contin-
ued)
Error
Error dis-
source ad-
play
dress
Heat M-NET re-
source mote con-
unit troller (RC)
(OC) MA remote
controller
(MA)
Indoor M-NET re-
unit mote con-
(IC) troller (RC)
MA remote
controller
(MA)
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).
Detection
Cause
method
No ac- Same cause as that for system with
knowl- one heat source unit
edgement
(ACK) at IC
transmis-
sion to OC
No ac- (1) Same causes as (1) - (5) for
knowl- system with one heat source unit
edgement (2) Disconnection or short circuit of
(ACK) at the transmission line for the heat
RC trans- source unit on the terminal block
mission to for centralized control line con-
IC nection (TB7)
(3) When multiple heat source units
are connected and the power
source of one of the heat source
units has been shut off.
(4) The male power supply connec-
tor of the heat source unit is not
connected to the female power
supply switch connector (CN40).
(5) The male power supply connec-
tors on 2 or more heat source
units are connected to the fe-
male power supply switch con-
nector (CN40) for centralized
control.
If an error occurs, after the unit runs
normally once, the following causes
may be considered.
Total capacity error (7100)
Capacity code error (7101)
Error in the number of con-
nected units (7102)
Address setting error (7105)
- 205 -
[ IX Troubleshooting ]
Check method and remedy
Same remedy as that for system with one
heat source unit
1) Turn off the power sources of the heat
source and indoor units for 5 or more
minutes, and turn them on again. If the
error is accidental, the will run normal-
ly.If not, check the cause 2).
2) Check the causes of (1) - (5). If the
cause is found, correct it. If no cause is
found, check 3).
3) Check the LED displays for trouble-
shooting on other remote controllers
whether an error occurs.
If an error is found,
-> If an error is found, check the check
code definition, and correct the error.
If no error is found,
-> Indoor unit board failure