Troubleshooting According To Malfunction Of The Remote Controller - Mitsubishi Electric PU(H)Y-P250YGM-A Service Handbook

4. Troubleshooting according to malfunction of the remote controller/main remote controller or the external input
error
(1) In the case of MA remote controller
Phenomena
1 Even if the operation button on
the remote controller is
pressed, the display remains
unlit and the unit does not start
running.(Power indicator
does not appear on the
screen.)
Cause
1. The power is not supplied to the
indoor unit.
(i) The main power of the in-
door unit is not on.
(ii) The connector (CND,
CNT, CN3T) on the indoor
unit board has come off.
(iii) The fuse on the indoor
unit board has melted.
(iv) Transformer failure and
disconnected wire of the
indoor unit.
2. Incorrect wiring for the MA remote
controller
(i) Disconnected wire for the
MA remote controller or dis-
connected line to the termi-
nal block.
(ii) Short-circuited MA remote
controller wiring
(iii) Reversed wiring between
wiring numbers of the MA
remote controller wiring
(iv) Incorrect wiring for the MA
remote controller to the ter-
minal block for transmission
line connection (TB5) on the
indoor unit
(v) Reversed connection of the
wire for the MA remote con-
troller and the AC220~240V
power wire
(vi) Reversed connection of
the wire for the MA remote
controller and the M-NET
transmission line on the in-
door unit
3. The number of the MA remote
controllers that are connected to
an indoor unit exceeds the allow-
able range (2 units).
4. The length or the diameter of the
wire for the MA remote controller
are out of specification.
5. Short circuit of the wire for the re-
mote display output of the outdoor
unit or reversed polarity connec-
tion of the relay.
6. The indoor unit board failure
7. MA remote controller failure
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[ IX Troubleshooting ]
Check method and remedy
(1) Measure voltages of the MA remote
controller terminal (among A to B).
If the voltage is between DC 8.5 and
12V, the remote controller is a failure.
If no voltage is applied
Check 1. 3. described on the left. If the
cause is found, correct it.
If no cause is found, refer to 2).
(2) Remove the wire for the remote control-
ler from the terminal block (TB13) on
the MA remote controller for the indoor
unit, and check voltage among A to B.
If the voltage is between DC 8.5 and
12V
Check the 2. 4. described on the left.
If no voltage is applied
Check 1. described on the left. If the
cause is found, correct it.
If no cause is found, check the wire for
the remote display output (the relay
polarity).
If no further cause is found, replace the
indoor unit board.