10
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Troubleshooting
Installer and user reference guide
43
R R8T7V1B
VRV IV heat pump for indoor installation
4P499898-1B – 2021.12
10.2.7 Symptom: White mist comes out of a unit (Indoor unit, heat exchanger unit)
When the system is changed over to heating operation after defrost operation.
Moisture generated by defrost becomes steam and is exhausted.
10.2.8 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. A power reset may help to remove this error.
10.2.9 Symptom: Noise of air conditioners (Indoor unit, heat exchanger 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 (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.
10.2.10 Symptom: Noise of air conditioners (Indoor unit, compressor unit, heat exchanger 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 the compressor
unit, heat exchanger unit and indoor 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.
10.2.11 Symptom: Noise of air conditioners (compressor unit, heat exchanger unit)
When the tone of operating noise changes. This noise is caused by the change of
frequency from the compressor or the fans.
10.2.12 Symptom: Dust comes out of the heat exchanger unit
When the unit is used for the first time in a long time. This is because dust has
gotten into the heat exchanger unit.
10.2.13 Symptom: The units can give off odours
The unit can absorb the smell of rooms, furniture, cigarettes, etc., and then emit it
again.
