Mitsubishi Electric PQHY-P120THMU-A, Service Handbook

Page: 281 / 414

[
IX
Troubleshooting ]
- 272 - HWE09080 GB
1. Error Code
No ACK error
2. 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 trans-
mitted six times in a row with 30 seconds interval, the error is detected on the transmission side.)
The address/attribute appeared on the display on the remote controller indicates the controller which did not provide
the response (ACK).
3. System configuration
(2) Grouping of units in a system with multiple heat source units
6607
Error
source
address
Error display
Detection
method
Cause Check method and remedy
ME re-
mote con-
troller
(RC) ME remote
controller (RC)
MA remote
controller (MA) No acknowl-
edgement
(ACK) at IC
transmission to
RC (1) Same causes as (1) - (4) for
system with one heat source
unit 1) Turn off the power source of
heat source unit for 5 or more
minutes, and turn it on again. If
the error is accidental, it will
run normally.If not, check the
cause 2).
(2) Disconnection or short circuit
of the transmission line for
the heat source unit on the
terminal block for centralized
control line connection (TB7) 2) Check the causes of (1) - (5). If
the cause is found, correct it. If
no cause is found, check 3).
(3) When multiple heat source
units are connected and the
power source of one of the
heat source units has been
shut off. 3) Same cause as that for indoor
unit described in 3)
(4) The male power supply con-
nector of the heat source unit
is not connected to the fe-
male power supply switch
connector (CN40).
(5) The male power supply con-
nectors on 2 or more heat
source units are connected to
the female power supply
switch connector (CN40) for
centralized control.
If the problem recurs after
normal operation is restored,
the problem is caused by one
of the following factors:
Œ
Total capacity error
(7100)
Œ
Capacity code setting
error (7101)
Œ
Error in the number of
connected units (7102)
Œ
Address setting error
(7105)