Mitsubishi Electric PUZ-WZ50VAA Service Manual page 40

Check code Abnormal points and detection method
Indoor/outdoor unit communication error
(Signal receiving error) (Outdoor unit)
Abnormal if outdoor controller circuit board
could not receive anything normally for 3
E8
minutes.
(6840)
Indoor/outdoor unit communication error
(Transmitting error) (Outdoor unit)
Abnormal if "0" receiving is detected
E9 30 times continuously though outdoor
controller circuit board has transmitted "1".
(6841)
Abnormal if outdoor controller
circuit board could not find blank of
transmission path for 3 minutes.
Non defined check code
EF
This code is displayed when non defined
(6607 check code is received.
or
6608)
Serial communication error
Abnormal if serial communication between
outdoor controller circuit board and
outdoor power circuit board is defective.
Ed
(0403)
OCH816
Cause
Contact failure of indoor/
outdoor unit connecting wire
Defective communication circuit
of outdoor controller circuit board
Defective communication circuit
of indoor controller board
Noise has entered into indoor/
outdoor unit connecting wire.
Indoor/ outdoor unit connecting
wire has contact failure.
Defective communication circuit
of outdoor controller circuit board
Noise has entered power supply.
Noise has entered indoor/
outdoor unit connecting wire.
Noise has entered transmission
wire of remote controller.
Noise has entered indoor/
outdoor unit connecting wire.
Outdoor unit is not inverter
models.
Breaking of wire or contact
failure of connector CN2
between the outdoor controller
circuit board and the outdoor
power circuit board
Breaking of wire or contact
failure of connector CN4
between the outdoor controller
circuit board and the outdoor
power circuit board
Defective communication circuit
of outdoor power circuit board
Defective communication circuit
of outdoor controller circuit board
for outdoor power circuit board
40
judgment and action
Check disconnection or looseness of indoor/
outdoor unit connecting wire of indoor or
outdoor units.
– Turn the power off, and on again to check.
Replace indoor controller board or outdoor
controller circuit board if abnormality is
displayed again.
Check disconnection or looseness of indoor/
outdoor unit connecting wire.
– Turn the power off, and on again to
check. Replace outdoor controller circuit
board if abnormality is displayed again.
Turn the power off, and on again to check.
Replace indoor controller board or outdoor
controller circuit board if abnormality is
displayed again.
Replace outdoor unit with inverter type
outdoor unit.
Check connection of each connector CN2
and CN4 between the outdoor controller
circuit board and the outdoor power circuit
board.
Replace outdoor power circuit board.
Replace outdoor controller circuit board.