Mitsubishi Electric MXZ-8A140VA1 Technical & Service Manual page 37

Abnormal point and detection method
Error Code
Indoor - branch box/branch box -
outdoor unit communication error
(Transmitting error)
(Branch box/outdoor unit)
(1) Abnormal if "0" receiving is detected 30
E9
times continuously though branch box/
(6841)
outdoor controller circuit board has
transmitted "1".
(2) Abnormal if branch box/outdoor control-
ler circuit board could not find blank of
transmission path for 3 minutes.
Non defined error code
This code is displayed when non defined
EF
error code is received.
(6607
or
6608)
Serial communication error
1. Abnormal if serial communication
between outdoor controller circuit
board and outdoor power circuit board
is defective.
Ed
(0403)
Forced compressor stop.
(Overlap malfunction of drain pump in
indoor unit and linear expansion valve in
branch box.)
PA
(2520)
When condition of the outdoor unit is
forcefully stopped, which means the drain
sensor detects continuously to go under
water 5 times, and also detects "[liquid
pipe temperature – suction temperature]
[ – 10deg" for 30 minutes continuously,
the indoor unit and indoor units in same
refrigerant system which operates in cool-
ing, heating or dry mode stops abnormally.
Also, the outdoor unit which is connected
to that indoor unit with refrigerant system
stops abnormally (compressor is sus-
pended to operate). In this time, <PA> is
displayed.
Case
1 Indoor–branch box/
branch box–outdoor unit con-
necting wire has contact failure.
2 Defective communication cir-
cuit of outdoor controller circuit
board
3 Noise has entered power sup-
ply.
4 Noise has entered Indoor–
branch box/branch box–
outdoor unit connecting wire.
1 Noise has entered transmission
wire of remote controller.
2 Noise has entered Indoor–
branch box/branch box–
outdoor unit connecting wire.
3 Model name of remote control-
ler is PAR-S25A.
1 Breaking of wire or contact fail-
ure of connector CN2 between
the outdoor controller circuit
board and the outdoor power
circuit board
2 Breaking of wire or contact fail-
ure of connector CN4 between
the outdoor controller circuit
board and the outdoor power
circuit board
3 Defective communication circuit
of outdoor power circuit board
4 Defective communication circuit
of outdoor controller circuit board
for outdoor power circuit board
1 Drain pump trouble
2 Drain defective
· Drain pump clogging
· Drain pipe clogging
3 Open circuit of drain sensor
side heater
4 Contact failure of drain sensor
connector
5 Dew condensation on drain
sensor
· Drain water descends along
lead wire.
· Drain water waving due to fil-
ter clogging
6 Indoor controller board defective
· Drain pump drive circuit failure
· Drain heater output circuit fail-
ure
7 Both of above mentioned 1~6
and the linear expansion valve
full closed failure happens syn-
chronistically.
37
Judgment and action
1 Check disconnection or looseness of indoor–
branch box/branch box–outdoor unit connect-
ing wire.
2~4 Turn the power off, and on again to
check. Replace outdoor controller circuit
board if abnormality is displayed again.
12 Turn the power off, and on again to check.
Replace indoor controller board or branch
controller board or outdoor controller circuit
board if abnormality is displayed again.
3 Replace remote controller with MA remote
controller.
12 Check connection of each connector CN2
and CN4 between the outdoor controller
circuit board and the outdoor power circuit
board.
3 Replace outdoor power circuit board.
4 Replace outdoor controller circuit board.
1 Check the drain pump.
Performance
2 Please confirm whether water can be
drained.
3 Confirm the resistance of the drain sensor
side heater.
4 Check the connector contact failure.
5 Check the drain sensor leadwire mounted.
Check the filter clogging.
6 If the above mentioned checkpoints has any
problem, replace the indoor controller board.
7 Check whether the indoor linear expansion
valve leaks or not.