Mitsubishi Electric PURY-P72 Service Handbook page 266

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[ IX Troubleshooting ]
-1- Troubleshooting according to the remote controller malfunction or the external input error
In the case of MA remote controller
1. Phenomena
Even if the operation button on the remote controller is pressed, the display remains unlit and the unit does not start run-
ning.(Power indicator
(1) Cause
1) The power is not supplied to the indoor unit.
The main power of the indoor unit is not on.
The connector on the indoor unit board has come off.
The fuse on the indoor unit board has melted.
Transformer failure and disconnected wire of the indoor unit.
2) Incorrect wiring for the MA remote controller
Disconnected wire for the MA remote controller or disconnected line to the terminal block.
Short-circuited MA remote controller wiring
Incorrect wiring of the MA remote controller cables
Incorrect connection of the MA remote wiring to the terminal block for transmission line (TB5) on the indoor unit
Wiring mixup between the MA remote controller cable and power supply cable
Reversed connection of the wire for the MA remote controller and the M-NET transmission line on the indoor unit
3) The number of the MA remote controllers that are connected to an indoor unit exceeds the allowable 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 remote display output of the outdoor unit or reversed polarity connection of the relay.
6) The indoor unit board failure
7) MA remote controller failure
(2) Check method and remedy
1) Measure voltages of the MA remote controller terminal (among 1 to 3).
If the voltage is between DC 9 and 12V, the remote controller is a failure.
If no voltage is applied, check the causes 1) and 3) and if the cause is found, correct it.
If no cause is found, refer to 2).
2) Remove the wire for the remote controller from the terminal block (TB13) on the MA remote controller for the indoor unit, and
check voltage among 1 to 3.
If the voltage is between DC 9 and 12 V, check the causes 2) and 4) and if the cause is found, correct it.
If no voltage is applied, check the cause 1) and if the cause is found, correct it.
If no cause is found, check the wire for the remote display output (relay polarity).
If no further cause is found, replace the indoor unit board.
HWE0803A
does not appear on the screen.)
- 257 -
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