Transmission Error Between Indoor Units And Outdoor Units - Daikin RXYQ-TA Series Service Manual

SiUS341615E
3.58 Transmission Error between Indoor Units and Outdoor
Units
U4
Error Code
Applicable All indoor unit models
All outdoor unit models
Models
Method of Error Microcomputer 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
Service Diagnosis
Short circuit in indoor-outdoor or outdoor-outdoor transmission wiring (F1 / F2), or wrong wiring
Outdoor unit power supply is OFF
System address does not match
Defective indoor unit PCB
Defective outdoor unit PCB
Be sure to turn off the power switch before connecting or disconnecting
Caution connectors, or parts may be damaged.
Check for details of error in
monitor mode.
U4-01
YES
Has the
indoor or
outdoor unit PCB
been replaced, or has
the indoor-outdoor or
outdoor-outdoor
transmission
wiring been
modified?
NO
Do all
indoor unit
remote controllers in
the same refrigerant
system display
U4?
YES
Reset the power supply once.
A
NO
YES
Are the
indoor-outdoor and
NO
outdoor-outdoor
transmission wirings
normal?
NO
Troubleshooting by Error Code
Refer to U4-03
troubleshooting.
(Indoor unit system
transmission error)
Press and hold BS3 on the
master outdoor unit main
PCB for a period of 5
seconds or more. (The
system will not operate for a
period of 12 minutes at
maximum.)
YES
Replace the indoor unit PCB.
Modify the transmission
wirings.
266