Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook page 313

[ IX Troubleshooting ]
Phenomena
3 "HO" or "PLEASE WAIT" dis-
play on the remote controller
does not disappear, and no op-
eration is performed even if the
button is pressed. ("HO" or
"PLEASE WAIT" display will
normally turn off 5 minutes lat-
er after the power on.)
Check method and remedy
Same symptom for all units in a
system with one outdoor unit?
Check the self-diagnosis LED
Is the error code 7120
Error found?
Check (1).
Refer to [4] .6. (2) "Outdoor unit transmission power source
circuit failure judgment" for the check method.
1. The power for the M-NET transmission line is not supplied from the outdoor unit.
2. Short-circuited transmission line
3. Incorrect wiring of the M-NET transmission line on the outdoor unit.
Disconnected wire for the MA remote controller or disconnected line to the ter-
minal block.
The indoor transmission line is connected incorrectly to the transmission termi-
nal block for centralized controller (TB7).
The male power supply connectors on the multiple outdoor units are connected
to the female power supply switch connector (CN40).
In the system to which the power supply unit for transmission lines is connect-
ed, the male power supply connector is connected to the female power supply
switch connector (CN40) on the outdoor unit
4. Disconnected M-NET transmission line on the indoor unit.
5. Disconnected wire between the terminal block for M-NET line (TB5) of the indoor
unit and the indoor unit board (CN2M) or disconnected connector.
6. Incorrect wiring for the MA remote controller
Short-circuited wire for the MA remote controller
Disconnected wire for the MA remote controller (No.2) and disconnected line
to the terminal block.
Reversed daisy-chain connection between groups
Incorrect wiring for the MA remote controller to the terminal block for transmis-
sion line connection (TB5) on the indoor unit
The M-NET transmission line is connected incorrectly to the terminal block
(TB13) for the MA remote controller.
7. The sub/main setting of the MA remote controller is set to sub.
8. 2 or more main MA remote controllers are connected.
9. Indoor unit board failure (MA remote controller communication circuit)
10.Remote controller failure
When 2. and 3. apply, check code 7102 will be displayed on the self-diagno-
sis LED.
NO
YES
YES
Check
2 and 3.
displayed?
NO
YES Replace the M-NET remote
controller with the MA
remote controller
NO
Cause
Check 4.
Correct
the error.
Correct
the error.
- 304 -
Measure voltages of the
terminal block for transmission
line (TB5) on the indoor unit.
NO
17 - 30V?
YES
Check for 5 and 6.
YES
Error found?
NO
Indoor unit board or
MA remote controller failure