Mitsubishi Electric M Series Service Manual page 34

Abnormal point and detection method
Error Code
Indoor/outdoor unit communication
error (Signal receiving error)
1 Abnormal if indoor controller board
cannot receive any signal normally for
six minutes after turning the power on.
2 Abnormal if indoor controller board
cannot receive any signal normally for
three minutes.
3 Consider the unit as abnormal under the
following condition: When two or more
indoor units are connected to an
E6
outdoor unit, indoor controller board
cannot receive a signal for three minutes
from outdoor controller circuit board, a
signal which allows outdoor controller
circuit board to transmit signals.
Indoor/outdoor unit communication
error (Transmitting error)
Abnormal if "1" receiving is detected 30
times continuously though indoor controller
board has transmitted "0".
E7
Indoor controller board
Abnormal if data cannot be read normally
from the nonvolatile memory of the indoor
controller board.
Fb
Remote controller control board
1 Abnormal if data cannot be read normal-
ly from the nonvolatile memory of the
remote controller control board.
(Error code: E1)
2 Abnormal if the clock function of remote
controller cannot be operated normally.
(Error code: E2)
E1
or
E2
Cause
1 Contact failure, short circuit or,
mis-wiring (converse wiring) of
indoor/outdoor unit connecting
wire
2 Defective transmitting receiving
circuit of indoor controller board
3 Defective transmitting receiving
circuit of indoor controller board
4 Noise has entered into indoor/
outdoor unit connecting wire.
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 Defective indoor controller
board
1 Defective remote controller
32
Countermeasure
Check LED display on the outdoor control cir-
cuit board. (Connect A-control service
tool, PAC-SK52ST.)
Refer to EA-EC item if LED displays EA-EC.
1 Check disconnection or looseness of indoor/
outdoor unit connecting wire of indoor unit or
outdoor unit.
Check all the units in case of twin triple
indoor unit system.
2-4 Turn the power off, and on again to check.
If abnormality generates again, replace
indoor controller board or outdoor
controller circuit board.
Other indoor controller board may have
defect in case of twin triple indoor unit
system.
1-3 Turn the power off, and on again to check.
If abnormality generates again, replace
indoor controller board.
1 Replace indoor controller board.
1 Replace remote controller.
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