Transmission Error Between Indoor Units And Outdoor Units - Daikin VRV IV-S RXTQ-TAVJU Series Service Manual

Troubleshooting by Error Code
4.41 Transmission Error between Indoor Units and Outdoor
Units
U4
Error Code
Applicable All indoor and outdoor units
Models
Method of Error Micro-computer checks if transmission between indoor and outdoor units is normal.
Detection
Error Decision
When transmission is not carried out normally for a certain amount of time
Conditions
Supposed
Causes
Troubleshooting
195
Indoor to outdoor, outdoor to outdoor transmission wiring F1, F2 disconnection, short circuit or
wrong wiring
Outdoor unit power supply is OFF
System address does not match
Defective indoor unit PCB
Defective outdoor main PCB
Be sure to turn off the power switch before connecting or disconnecting
Caution connectors, or parts may be damaged.
Has
the indoor
or outdoor unit
PCB been replaced,
or has the indoor - outdoor
or outdoor - outdoor unit
transmission wiring
been modified?
NO
All indoor
unit remote
controllers of the same
refrigerant system
U4
display .
YES
Reset the power supply.
A
YES
Is indoor -
outdoor and outdoor -
NO
outdoor unit transmission
wiring normal?
NO
SiUS331604E
Press and hold the RESET
button on the master outdoor
unit PCB for 5 seconds.
∗ The unit will not operate for
up to 12 minutes.
YES
Replace the indoor unit PCB
indicated by the error code
U4
.
Fix the indoor-outdoor or
outdoor-outdoor unit
transmission wiring.
Service Diagnosis