Indoor/Outdoor Unit Communication - Mitsubishi Electric SUZ-KA24NAHZ Service Manual

Check Code Abnormal point and detection method
Remote controller transmission
error(E3)/signal receiving error(E5)
1 Abnormal if remote controller could not
find blank of transmission path for 6 sec-
onds and could not transmit.
(Check code: E3)
2 Remote controller receives transmitted
data at the same time, compares the
data, and when detecting it, judges
E3
different data to be abnormal 30
or
continuous times. (Check code: E3)
E5
1 Abnormal if indoor controller board could
not find blank of transmission path.
(Check code: E5)
2 Indoor controller board receives trans-
mitted data at the same time, compares
the data,and when detecting it, judges
different data to be abnormal 30
continuous times. (Check code: E5)

Indoor/outdoor unit communication

error (Signal receiving error)
1 Abnormal if indoor controller board could
not receive any signal normally for 6
minutes after turning the power on.
2 Abnormal if indoor controller board could
not receive any signal normally for 3
minutes.
3 Consider the unit as abnormal under
the following condition When 2 or more
indoor units are connected to an out-
door unit, indoor controller board could
not receive a signal for 3 minutes from
E6
outdoor controller circuit board, a signal
(6840)
which allows outdoor controller circuit
board to transmit signals.
Indoor/outdoor unit communication
error (Transmitting error)
Abnormal if "1" receiving is detected 30
E7
times continuously though indoor controller
board has transmitted "0".
Indoor/outdoor unit communication
error (Signal receiving error)
(Outdoor unit)
Abnormal if outdoor controller circuit board
E8
could not receive anything normally for 3
(6840)
minutes.
Indoor/outdoor unit communication
error (Transmitting error) (Outdoor unit)
1 Abnormal if "0" receiving is detected 30
times continuously though outdoor con-
troller circuit board has transmitted "1".
2 Abnormal if outdoor controller circuit
E9
board could not find blank of transmis-
(6841)
sion path for 3 minutes.
OCH754A
Cause
1 2 remote controllers are set as
"main." (In the case of 2 remote
controllers)
2 Remote controller is connected
with 2 indoor units or more.
3 Repetition of refrigerant
address
4 Defective transmitting receiving
circuit of remote controller
5 Defective transmitting receiving
circuit of indoor controller board
6 Noise has entered into trans-
mission wire of remote control-
ler.
1 Contact failure, short circuit or
miswiring (converse wiring) of
indoor/outdoor unit connecting
wire
2 Defective transmitting receiv-
ing circuit of outdoor controller
circuit board.
3 Defective transmitting receiv-
ing circuit of indoor controller
board.
4 Noise has entered into indoor/
outdoor unit connecting wire.
5 Defective fan motor
6 Defective rush current resistor
of outdoor power circuit board.
1 Defective transmitting receiving
circuit of indoor controller board
2 Noise has entered into power
supply.
3 Noise has entered into outdoor
control wire.
1 Contact failure of indoor/out-
door unit connecting wire
2 Defective communication cir-
cuit of outdoor controller circuit
board
3 Defective communication circuit
of indoor controller board
4 Noise has entered into indoor/
outdoor unit connecting wire.
1 Indoor/outdoor unit connecting
wire has contact failure.
2 Defective communication cir-
cuit of outdoor controller circuit
board
3 Noise has entered power supply.
4 Noise has entered indoor/ out-
door unit connecting wire.
33
Judgment and action
1 Set a remote controller to main, and the
other to sub.
2 Remote controller is connected with only one
indoor unit.
3 The address changes to a separate setting.
4–6 Diagnose remote controller.
a) When "OK" is displayed, remote control-
lers have no problem.
Turn the power off, and on again to check.
When becoming abnormal again, replace
indoor controller board.
b) When "NG" is displayed, replace remote
controller.
c) When "E3"or "ERC" is displayed, noise
may be causing abnormality.
Note: Check LED display on outdoor controller
circuit board. (Connect A-Control service
tool (PAC-SG50ST))
Refer to EA−EC item if LED displays EA−AC.
1 Check disconnecting or loosenness of indoor
/outdoor unit connecting wire of indoor unit
or outdoor unit.
Check all the units in the case of twin indoor
unit system.
2–4 Turn the power off, and on again to check.
If abnormality occurs again, replace indoor
controller board or outdoor controller
circuit board.
5 Turn the power off, and detach fan motor
from connector (CNF1,2). Then turn the
power on again.
If abnormality is not displayed, replace fan motor.
If abnormality is displayed, replace outdoor
controller circuit board.
6 Check the rush current resistor on outdoor
noise filter board with a tester. If open is
detected, replace the power board.
Note: Other indoor controller board may have
defect in the case of twin indoor unit system.
1–3 Turn the power off, and on again to
check. Replace indoor controller board if
abnormality is displayed again.
1 Check disconnection or looseness of indoor/
outdoor unit connecting wire of indoor or out-
door units.
2–4 Turn the power off, and on again to
check. Replace indoor controller board or
outdoor controller circuit board if abnor-
mality is displayed again.
1 Check disconnection or looseness of indoor/
outdoor unit connecting wire.
2–4 Turn the power off, and on again to
check. Replace outdoor controller circuit
board if abnormality is displayed again.