Mitsubishi Electric PUHY-P200 Service Handbook page 125

Phenomena
3 "HO" display on the remote
controller does not turn off,
and the switch does not work.
("HO" display turn off 3
minutes later, after turning the
power on.)
Check method & Handling
Same symptom
for all units in a single
refrigerant system?
YES
Self-diagnosis LED
checks
7120 error display?
NO
Problems?
NO
Check for Item (1)
For the check method, follow
"Outdoor unit transmission power
source circuit failure judgment"
(1) The power for the M-NET transmission line is not
supplied from the outdoor unit.
(2) Short circuit of the transmission line.
(3) Incorrect wiring of the M-NET transmission line on
the outdoor unit side.
1 Disconnected wire for the MA remote controller
and disconnected line to the terminal block.
2 The indoor transmission line is connected
incorrectly to terminal block (TB7) to the
transmission line for centralized control.
3 The power supply connectors (CN40) for multiple
outdoor units are inserted.
Or the power supply connector (CN40) for
outdoor unit is inserted in the system to which
the power supply unit for transmission line is
connected.
(4) Disconnected M-NET transmission line on the
indoor unit side.
(5) Disconnected wire between terminal block (TB5) to
the M-NET transmission line of the indoor unit and
the indoor controller board (CN2M) or disconnected
connector.
(6) The wire for the MA remote controller is connected
incorrectly.
1 Short circuit of the wire for the MA remote
controller.
2 Disconnected wire for the MA remote controller
(No.2) and disconnected line to the terminal
block.
3 Reversed connection under group control.
4 The wire for the MA remote controller is
connected incorrectly to the terminal block to the
transmission line (TB5).
5 The M-NET transmission line is connected
incorrectly to the terminal block (TB13) on the
MA remote controller.
(7) The sub/main setting of the MA remote controller is
set to sub.
(8) More than 2 main MA remote controllers are
connected.
(9) Indoor unit controller board failure (MA remote
controller communication line)
(10) Remote controller failure.
NO
YES
Check for the Factor
(2) and (3)
Replace the M-NET
YES
remote controller
with the MA remote
controller
Handle the problems
9.[4].7.(2)
- 123 -
Factors
When the factor
(2) and (3) apply,
self-diagnosis
LED works and
the check code
7102 will be
displayed.
Check voltage of the terminal
block (TB5) to the transmission
line of the indoor unit
NO
Check for Item (4)
Check for Item (5)
YES
Handle the problems
Failure of the indoor unit
controller board or the MA
remote controller
17-30V?
YES
Problems?
NO