Troubleshooting; Diagnostic Procedure For Check Code - Toshiba HFC R407C Service Manual

Check code
[04]
Inverter serial signal
short circuit
Inter-unit communication
Is there continuity of the
communication cable between
the indoor unit and Multi
Controller?
Yes
Is there continuity of the
communication cable between
the Multi Controller the outdoor
unit
Yes
Is there continuity of the
communication cable between
the outdoor interface PC board
and outdoor IPDU PC board?
Yes
Is there voltage present
between pins 4 and 5 of CN1
on communication PC board?
(DC 0 to 5 V, pin 5-GND)
Yes
Is there voltage present
between pins 3 and 5 of CN1
on interface PC board?
(DC 0 to 5 V, pin 5-GND)
Yes
Check noise interference from
outside, etc.
Yes
Is refrigerant detector
RBC-RD2-PE fitted?
Yes
Are the high level alarm and
the shutdown LEDs on the
RBC-RD2-PE (RED) on?
Yes
Refrigerant leak.
Leak-check unit.

Troubleshooting

Diagnostic procedure for check code

Status of air conditioner
Outdoor unit stops
Indoor unit fan continues
No
No
No
No
No
No
No
Operation cause
1. Wiring fault between indoor and Multi
Controller or Multi Controller and outdoor
interface PC board.
2. Defective communication PC board.
3. Defective IPDU PC board.
4. Noise from outside.
5. High level refrigeration leak (RBC-RD2-PE).
Replace communication cable
Replace communication cable
Replace communication cable
Communication PC board is defective - replace
IPDU PC board is defective - replace
Complete checks detailed above
Complete checks detailed above
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