Daikin FCAHG71HVEB - Symptom: the User Interface Reads U4 or U5 and Stops, but then Restarts after a few Minutes; Symptom: Noise of Air Conditioners (Indoor Unit); Symptom: Noise of Air Conditioners (Indoor Unit, Outdoor Unit); Symptom: Noise of Air Conditioners (Outdoor Unit)

18 | Troubleshooting
Installer and user reference guide
77
FCAHG71~140HVEB
Split system air conditioners
4P561449-1B – 2021.07
18.1.6 Symptom: The user interface reads "U4" or "U5" and stops, but then restarts after a few
minutes
This is because the user interface is intercepting noise from electric appliances
other than the air conditioner. The noise prevents communication between the
units, causing them to stop. Operation automatically restarts when the noise
ceases.
18.1.7 Symptom: Noise of air conditioners (Indoor unit)
▪ A "zeen" sound is heard immediately after the power supply is turned on. The
electronic expansion valve inside an indoor unit starts working and makes the
noise. Its volume will reduce in about one minute.
▪ A continuous low "shah" sound is heard when the system is in cooling operation
or at a stop. When the drain pump is in operation, this noise is heard.
▪ A "pishi-pishi" squeaking sound is heard when the system stops after heating
operation. Expansion and contraction of plastic parts caused by temperature
change make this noise.
18.1.8 Symptom: Noise of air conditioners (Indoor unit, outdoor unit)
▪ A continuous low hissing sound is heard when the system is in cooling or defrost
operation. This is the sound of refrigerant gas flowing through both indoor and
outdoor units.
▪ A hissing sound which is heard at the start or immediately after stopping
operation or defrost operation. This is the noise of refrigerant caused by flow
stop or flow change.
18.1.9 Symptom: Noise of air conditioners (Outdoor unit)
When the tone of operating noise changes. This noise is caused by the change of
frequency.
18.1.10 Symptom: Dust comes out of the unit
When the unit is used for the first time in a long time. This is because dust has
gotten into the unit.
18.1.11 Symptom: The units can give off odours
The unit can absorb the smell of rooms, furniture, cigarettes, etc., and then emit it
again.
18.1.12 Symptom: The outdoor unit fan does not spin
During operation. The speed of the fan is controlled in order to optimise product
operation.
18.1.13 Symptom: The display shows "88"
This is the case immediately after the main power supply switch is turned on and
means that the user interface is in normal condition. This continues for 1minute.