Daikin FTXF25B - U4-00 - Indoor;Outdoor Unit Communication Problem

1 | Troubleshooting
Service manual
27
FTXF20~71A + FTXF20~25B + FTXF20~42C + ATXF20~71A + ATXF20~42C
+ RXF20~71A + RXF20~60B + RXF20~42C + ARXF20~71A + ARXF20~42C
Split Sensira R32
ESIE18-12E – 2021.02
3 Perform a check of the outdoor unit fan motor. See "2.9 Outdoor unit fan
motor"[492].
Possible cause: Faulty outdoor unit fan motor.
4 Perform a check of the main PCB. See "2.8Main PCB"[474].
Possible cause: Faulty main PCB.
5 Wait until the compressor restarts.
Possible cause:
▪ Momentary drop of voltage,
▪ Momentary power failure.
INFORMATION
If all procedures listed above have been performed and the problem is still present,
contact the helpdesk.
1.5.29 U4-00 – Indoor/outdoor unit communication problem
Trigger Effect Reset
Communication failure
between outdoor and
indoor unit.
Unit will stop operating. Power reset via outdoor
unit.
To solve the error code
INFORMATION
It is recommended to perform the checks in the listed order.
1 Check if the power supply is conform with the regulations. See "3.1Electrical
circuit"[4127].
Possible cause:
▪ Faulty or disturbance of the power supply (imbalance >4%),
▪ Power drop,
▪ Short circuit.
2 Perform a check of the power supply, connections, wiring,… between the
outdoor unit and the indoor unit. See "3.1Electrical circuit"[4127].
Possible cause: Faulty wiring between the outdoor unit and the indoor unit.
3 Perform a check of the main PCB. See "2.8Main PCB"[474].
Possible cause: Faulty main PCB.
4 Perform a check of the outdoor unit fan motor. See "2.9 Outdoor unit fan
motor"[492].
Possible cause: Faulty outdoor unit fan motor.
5 Perform a check of the indoor unit main PCB. See "2.6 Indoor unit main
PCB"[467].
Possible cause: Faulty indoor unit main PCB.
Prerequisite: Stop the unit operation via the user interface.
6 Turn OFF the respective circuit breaker.