Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook page 317

[ IX Troubleshooting ]
Phenomena
3 "HO" display on the remote
controller does not disappear,
and no operation is performed
even if the button is pressed.
Check method and remedy
Without using MELANS
Are all the units in the system
experiencing the same problem?
Check the address of
the outdoor unit.
51 - 100?
Check the centralized centralized
switch (SW2-1) on the outdoor unit.
Indoor unit main board failure
*1. When the indoor unit address is set to 1 - 50, the address will be forcibly set to 100.
Using MELANS
When MELANS is used, "HO" display on the remote controller will disappear when the indoor unit and the local remote controller
(M-NET remote controller) are grouped.
If "HO" does not disappear after the registration, check the 11. - 13.
Without using MELANS
1. Outdoor unit address is set to "00"
2. A wrong address is set.
A wrong address is set to the indoor unit to be coupled with the remote controller.
100 must be subtracted from the address of the M-NET remote controller.
A wrong address is set to the M-NET remote controller
(100 must be added to the address of the indoor unit.)
3. Faulty wiring of the terminal block for transmission line (TB5) of the indoor unit in the same group
with the remote controller.
4. The centralized control switch (SW2-1) on the outdoor unit is set to ON.
5. Disconnection or faulty wiring of indoor unit transmission line.
6. Disconnection between the terminal block for M-NET line connection (TB5) of the indoor unit and
the male connector (CN2M)
7. The male power supply connectors on 2 or more outdoor units are connected to the female pow-
er supply switch connector (CN40) for the transmission line for centralized control.
8. Outdoor unit main board failure
9. Indoor unit board failure
10.Remote controller failure
Interlocking control with MELANS
11.No group registration is made using MELANS. (The indoor unit and the M-NET remote controller
are not grouped.)
12.Disconnected transmission line for centralized control (TB7) of the outdoor unit
13.In the system to which the power supply unit for transmission lines is connected, the male power
supply connector is connected to the female power supply switch connector (CN40) on the out-
door unit
NO
YES
*1
NO
A wrong address is
set to the outdoor unit.
YES
YES
Wrong switch setting
ON?
Change it from
ON to OFF.
NO
Cause
NO
A wrong address is
set to the M-NET
remote controller.
NO
A wrong address is
set to the indoor unit.
Wrong wiring of the
NO
M-NET transmission
line of the indoor unit
YES
Disconnected
connector (CN2M)
Correct
the error.
- 308 -
Check the address of the M-NET remote
controller on which "HO" is displayed.
Indoor unit + 100?
YES
Check the address of the
indoor unit to be coupled.
M-NET remote controller
- 100?
YES
Measure voltages of the terminal
block for transmission line (TB5)
on the indoor unit.
17 - 30V?
YES
Check connection between indoor M-NET
transmission terminal block (TB5) and the
male connector (CN2M)
Disconnected?
NO
Indoor unit board or
remote controller failure