Daikin R407C PLUS - Malfunction of Transmission between Indoor Units

Si33-105 Troubleshooting
Troubleshooting R407C PLUS Series Heat Recovery System 183
3.27 Malfunction of Transmission Between Indoor Units
Remote
Controller
Display
U4
Supposed
Causes
!
Indoor to outdoor, outdoor to outdoor crossover wiring disconnection, short circuit or wrong
check
!
Outdoor unit power supply is OFF
!
System address doesn’t match
!
Defect of indoor unit PC board
!
Defect of outdoor unit PC board
Troubleshooting
(VF054)
Is
indoor - outdoor and
outdoor - outdoor unit
transmission wiring
normal?
Supply 220~240 V.
Replace the fuse.
Fix the indoor/outdoor unit
transmission wiring.
Replace the outdoor unit
PC Board (A1P).
YES
NO
YES
Replace the indoor unit PC
Board.
Push and hold the RESET
button on the outdoor unit
PC Board for 5 seconds.
Fix the indoor/outdoor unit
transmission wiring.
YES
NO
NO
YES
Has
the indoor or
outdoor unit PC
board been replaced,
or has the indoor - outdoor or
outdoor - outdoor unit
transmission wiring
been modified?
All
indoor unit
remote controllers of the
same refrigerant system
display "U4."
NO
Outdoor unit PC
board microcomputer monitor
(HAP) blinks.
NO
NO
Operation
ready lamp (H2P) is
blinking.
Is indoor
- outdoor and outdoor -
outdoor unit transmission
wiring normal?
YES
The fuse on
the outdoor unit's PC board
is burnt.
Replace the transformer.
replacement
Replace outdoor unit PC
board. (A1P)
NO
The secondary
voltage of the transformer is
about 30 V.
NO
The voltage
between terminals R
and S of the outdoor unit PC
board is 220~240 V
(60Hz) or 220 V
(50 Hz).
Reset the power supply.
YES
YES
YES
NO
YES
Wait to lamp goes off.
H The unit will not
operate for up to 12
minutes.
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.