Symptom: White Mist Comes Out Of A Unit (Indoor Unit); Symptom: White Mist Comes Out Of A Unit (Indoor Unit, Outdoor Unit); Symptom: The User Interface Reads "U4" Or "U5" And Stops, But Then Restarts After A Few Minutes; Symptom: Noise Of Air Conditioners (Indoor Unit) - Daikin VRV IV Q+ Series Installer And User Reference Manual

11.2.6 Symptom: White mist comes out of a unit (Indoor unit)

11.2.7 Symptom: White mist comes out of a unit (Indoor unit, outdoor unit)

11.2.8 Symptom: The user interface reads "U4" or "U5" and stops, but then restarts after a few
minutes

11.2.9 Symptom: Noise of air conditioners (Indoor unit)

11.2.10 Symptom: Noise of air conditioners (Indoor unit, outdoor unit)

11.2.11 Symptom: Noise of air conditioners (Outdoor unit)

RXYQQ8~20U7Y1B
VRV IV Q+ series heat pump
4P546229-1A – 2020.10
▪ When humidity is high during cooling operation. If the interior of an indoor unit is
extremely contaminated, the temperature distribution inside a room becomes
uneven. It is necessary to clean the interior of the indoor unit. Ask your dealer for
details on cleaning the unit. This operation requires a qualified service person.
▪ Immediately after the cooling operation stops and if the room temperature and
humidity are low. This is because warm refrigerant gas flows back into the indoor
unit and generates steam.
When the system is changed over to heating operation after defrost operation.
Moisture generated by defrost becomes steam and is exhausted.
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.
▪ 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 (optional accessories) 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.
▪ A low "sah", "choro-choro" sound is heard while the indoor unit is stopped.
When another indoor unit is in operation, this noise is heard. In order to prevent
oil and refrigerant from remaining in the system, a small amount of refrigerant is
kept flowing.
▪ 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.
When the tone of operating noise changes. This noise is caused by the change of
frequency.
11 Troubleshooting
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Installer and user reference guide
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