Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 246

Error
Error definition and error detec-
Code tion method
6602 Transmission processor hard-
ware error
Although "0" was surely trans-
mitted by the transmission pro-
cessor, "1" is displayed on the
transmission line
Note: The address/attribute
appeared on the display
on the remote controller
indicates the controller
where an error oc-
curred.
Check method and remedy
(1) When the wiring work of or the polarity of either the indoor or heat source
transmission line is performed or is changed while the power is on, the trans-
mitted data will collide, the wave shape will be changed, and an error will be
detected.
(2) Grounding fault of the transmission line
(3) When grouping the indoor units that are connected to different heat source
units, the male power supply connectors on the multiple heat source units are
connected to the female power supply switch connector (CN40).
(4) When the power supply unit for transmission lines is used in the system con-
nected with MELANS, the male power supply connector is connected to the
female power supply switch connector (CN40) on the heat source unit.
(5) Controller failure of the source of the error
(6) When the transmission data is changed due to the noise on the transmission
line
(7) Voltage is not applied on the transmission line for centralized control (in case
of grouped indoor units connected to different heat source units or in case of
the system connected with MELANS)
Check method and remedy
Is the transmission line work
performed while the power is on?
NO
Check the power source of the indoor unit.
208 / 230V?
YES
Check the transmission line work is performed
and the shielded wire is treated properly.
Grounding fault or does the shielded
wire contact with the transmission line?
NO
System ?
Single-heat source-unit system Multiple-heat source-unit system
Confirm that the power supply
connector on the heat source
unit is not plugged into CN40.
Is the male power supply connector
YES
connected to the female power supply
switch connector (CN40) on only one
of the heat source unit?
Tightly reconnect the male power
supply connector to the female
power supply switch connector (CN40).
Investigation into the
*For the investigation method, follow
transmission line noise
<Investigation method of transmission wave shape/noise>
YES
Noise exist?
NO
Controller failure of the
source of the error
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[ IX Troubleshooting ]
YES
Turn off the power source of heat source
/indoor units, and turn them on again.
NO
Faulty power source work
YES
Improper transmission line work
System with the power supply
unit for transmission lines
Confirm that the power supply
connector on the heat source
unit is not plugged into CN40.
Is the male power supply connector
NO
connected to the female power supply
switch connector (CN40) ?
NO
Disconnect the male
power supply on
CN40 and connect it to CN41
Investigation into the
cause of the noise
Correct the error.
YES