what does U4 mean on a Daikin FTKZ09VV2S or FTKZ12VV2S?
U4 concerns failed communication between the indoor and outdoor units on Daikin FTKZ09VV2S and FTKZ12VV2S. it is not the same as a flat remote battery or an unresponsive remote.
model scope: Daikin FTKZ09VV2S and FTKZ12VV2S.
use the linked reporting guide to record a safely confirmed fault, then stop operation and supply the exact model to an air-conditioning technician. do not order a control board or remote solely because U4 appears; the cause still needs diagnosis.
keep covers closed and leave wiring and connection checks to qualified service. repeated resets do not establish that communication has been repaired. a code merely passed during scanning is not a confirmed fault without the model's long-beep indication.
for a burning smell, water leakage or recurring breaker trip, stop and isolate safely instead of running another check. this article does not transfer U4 meaning to the australian Cora family or other units.
possible causes
- a communication fault between the indoor and outdoor units that needs service assessment
solutions
diy warning
working on appliances can involve mains electricity, water and moving parts. always disconnect power and water before you start. in Australia, gas work must be done by a licensed gasfitter, and fixed (hard-wired) electrical work by a licensed electrician. everything on this site is guidance only, and any repair you carry out is at your own risk. we are not responsible for any damage or injury caused by attempting a repair. if you are not confident, please use a qualified technician.
