Mitsubishi Electric PURY-P72TYJMU-A Service Handbook page 209

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[ IX Troubleshooting ]
1. Error Code
0403
(YJMU-A)
Serial communication error
2. Error definition and error detection method
Serial communication error between the control board and the INV board on the compressor, and between the control board
and the Fan board
Detail code 01: Between the control board and the INV board
Detail code 05: Between the control board and the Fan board
3. Cause, check method and remedy
(1) Faulty wiring
Check the following wiring connections.
1) Between Control board and Fan board
Control board FAN board
CN2
CN21
CN4
CN5
CN332
CN18V
2) Between Fan board and INV board
FAN board
INV board
CN22
CN2
CN5V
CN4
CN4
(2) INV board failure, Fan board failure and Control board failure
Replace the INV board or the Fan board or control board when the power turns on automatically, even if the power source is
reset.
1. Error Code
0403
(YJMU-A)
Panel communication error
2. Error definition and error detection method
This error is detected when indoor units cannot successfully receive the signals from the Auto filter cleaning unit for one min-
ute.
3. Cause, check method and remedy
Cause
(1)
Incorrect switch setting on the indoor unit cir-
cuit board
(2)
Power wire that connects the circuit board on
the indoor unit and the circuit board on the
cleaning unit is loose.
(3)
Communication wire that connects the circuit
board on the indoor unit and the circuit board
on the cleaning unit is loose.
(4)
Panel transceiver circuit fault (cleaning unit)
(5)
Panel transceiver circuit fault (indoor unit)
(6)
Electrical interference on the cleaning unit's
communication cable
Refer to section -7- "Inverter (YJMU-A)" under part [4] Troubleshooting Principal Parts for error codes related to the
inverter.(page 320)
HWE0913A
(Indoor unit)
- 200 -
Check method and remedy
Check SW3-3 on the indoor unit circuit board
Set SW3-3 to ON only when connecting an auto filter cleaning
unit.
Check the LED1 (cleaning unit circuit board (microcomputer
power)).
Lit: Power is supplied properly.
Unlit: Check for loose or disconnected power wire between the
indoor unit circuit board (CNAC) and the cleaning unit circuit
board (CN3A).
Check the LED4 (cleaning unit circuit board (communication)).
Blinking: Normal communication
Unlit: Check for loose or disconnected communication wire be-
tween the indoor unit circuit board (CN3G) and the cleaning unit
circuit board (CN3G).
If the LED blinks at irregular intervals (normally blinks at 0.5-sec-
ond intervals), electrical interference is suspected.
Check the items above, turn the power off, and turn the power
back on. If the error persists, replace either the cleaning unit cir-
cuit board or the indoor unit circuit board.
GB

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