Mitsubishi Electric MXZ-8B140VA Technical & Service Manual page 25

Abnormal point and detection method
Error Code
Indoor–branch box/branch box–outdoor
unit connector miswiring, excessive
number of units
Outdoor/branch box controller circuit board
can automatically check the number of
connected indoor units. Abnormal if the
number cannot be checked automatically
due to miswiring of indoor– branch box/
branch box–outdoor unit connecting wire
and etc. after power is turned on for 4 min-
utes.
EA
(6844)
Miswiring of indoor–branch box/branch
box–outdoor unit
connecting wire (converse wiring or dis-
connection)
Outdoor/branch box controller circuit board
can automatically set the unit number of
indoor units.
Abnormal if the indoor unit number can
not be set within 4 minutes after power
Eb
on because of miswiring (converse wiring
(6845)
or disconnection) of indoor–branch box/
branch box–outdoor unit connecting wire.
Start-up time over
The unit cannot finish start-up process
within 4 minutes after power on.
EC
(6846)
OCH480A
Case
1 Contact failure or miswiring of
indoor/outdoor unit connecting
wire
2 Diameter or length of indoor–
branch box/branch box–out-
door unit connecting wire is out
of specified capacity.
There are 9 or more indoor
units in the system.
There are 3 or more branch
boxes in the system.
More than two P100 indoor
units are connected to the
branch box.
3 Defective transmitting receiving
circuit of outdoor/branch box
controller circuit board
4 Defective transmitting receiv-
ing circuit of branch box/indoor
controller board
5 Defective branch box/indoor
power board
6 Noise has entered into power
supply or indoor–branch box/
branch box–outdoor unit con-
necting wire.
1 Contact failure or miswiring of
indoor–branch box/branch box
–outdoor unit connecting wire
2 Diameter or length of indoor–
branch box/branch box–out-
door unit connecting wire is out
of specified capacity.
4 Defective transmitting receiving
circuit of outdoor/branch box
controller circuit board
5 Defective transmitting receiv-
ing circuit of indoor/branch box
controller board
6 Defective indoor/branch box
power board
7 Noise has entered into power
supply or indoor –branch box/
branch box–outdoor unit con-
necting wire.
1 Contact failure of indoor–
branch box/branch box–outdoor
unit connecting wire
2 Diameter or length of indoor–
branch box/branch box–outdoor
unit connecting wire is
out of specified capacity.
3 Noise has entered into power
supply or indoor–branch box/
branch box–outdoor unit con-
necting wire.
25
Judgment and action
1 Check disconnection or looseness or polar-
ity of indoor –branch box/branch box–outdoor
unit connecting wire of indoor and outdoor
units.
Before connecting P100 indoor unit(s), check
the requirements described in "9-2. Wiring to
P100 indoor units".
2 Check diameter and length of indoor–branch
box/branch box –outdoor unit connecting wire.
Total wiring length: 55 m (outdoor–branch box)
(including wiring connecting each branch box
unit and between branch box and outdoor
unit)
Also check if the connection order of flat
cable is S1, S2, S3.
If the error "EA" is detected, check the
number of the indoor units, the branch box
and P100 indoor unit(s) in the system.
3~5 Turn the power off once, and on again to
check.
Replace outdoor controller circuit board,
branch box controller board, indoor controller
board or indoor power board if abnormality
occurs again.
6 Check transmission path, and remove the
cause.
w The descriptions above, 1-6, are for EA, Eb
and EC.