U4-00 - Indoor/Outdoor Unit Communication Problem - Daikin Sky Air FAA71BUV1B Service Manual

3.3.19 U4-00 – Indoor/outdoor unit communication problem
FAA71+100BUV1B
Sky Air indoor units
ESIE22-01 – 2022.02
INFORMATION
If all procedures listed above have been performed and the problem is still present,
contact the helpdesk.
Trigger
Communication failure
between outdoor and
indoor unit.
To solve the error code
INFORMATION
It is recommended to perform the checks in the listed order.
1 Check if the power supply to the outdoor unit is compliant with the
regulations. See outdoor unit service manual.
Possible cause:
▪ Faulty or disturbance of the power supply (power supply MUST be within
range of nominal operating voltage ±4%),
▪ Power drop,
▪ Short circuit.
2 Perform a check of the power supply, connections, wiring,... between the
outdoor unit and the indoor unit. See
Possible cause: Faulty wiring between the outdoor unit and the indoor unit.
3 Perform a check of the main PCB A1P. See outdoor unit service manual.
Possible cause: Faulty main PCB.
4 Perform a check of the outdoor unit fan motor. See outdoor unit service
manual.
Possible cause: Faulty outdoor unit fan motor.
5 Perform a check of the indoor unit main PCB. See
4
PCB" [ 53].
Possible cause: Faulty indoor unit main PCB.
6 Check that "standby electricity saving mode" is OFF. See installation manual.
Possible cause: "Standby electricity saving mode" is ON, while this mode is
ONLY compatible with Split indoor units.
Prerequisite: Stop the unit operation via the user interface.
Prerequisite: Turn OFF the respective circuit breaker.
7 Wait until the rectifier voltage is below 10 V DC.
DANGER: RISK OF ELECTROCUTION
Wait for at least 10 minutes after the circuit breaker has been turned OFF, to be sure
the rectifier voltage is below 10 V DC before proceeding.
8 Check that the thermal interface grease is applied properly on the (PCB or
refrigerant piping) contact surface of the heat sink. Adjust if needed.
Effect
Unit will stop operating.
"5.1 Electrical
3 Troubleshooting
|
Reset
Power reset via outdoor
unit.
4
circuit" [ 83].
"4.5 Indoor unit main
Service manual
35