The Following Phenomena Do Not Represent Trouble (Emergency) - Mitsubishi Electric CITY MULTI PQRY-P250 Installationshandbuch

10.5. The following phenomena do not represent trouble (emergency)

Phenomenon
Indoor unit and BC controller generate
sound at the cooling/heating change
over sometime.
Indoor unit does not the perform cool-
ing (heating) operation.
The auto vane runs freely.
Fan setting changes during heating.
Fan stops during heating operation.
Fan does not stop while operation has
been stopped.
No setting of fan while start SW has
been turned on.
Heat source unit does not operate by
turning switch on.
Indoor unit remote controller shows
"HO" indicator for about two minutes
when turning ON universal power sup-
ply.
Drain pump does not stop while unit has
been stopped.
Drain pump continues to operate while
unit has been stopped.
Display of remote controller
Normal display
"Cooling (heating)" flashes
Normal display
Normal display
Defrost display
No lighting
Heat ready
Normal display
"HO" flashes
Light out
Cause
This is not a trouble as it is just a selecting sound.
When multiple indoor units (max. 3) are connected to the same branch
of the BC controller, the heating (cooling) operation cannot be per-
formed while another indoor unit is performing a cooling (heating) op-
eration.
Because of the control operation of auto vane, it may change over to
horizontal blow automatically from the downward blow in cooling in case
the downward blow operation has been continued for 1 hour. At de-
frosting in heating, hot adjusting and thermostat OFF, it automatically
changes over to horizontal blow.
Ultra-low speed operation is commenced at thermostat OFF.
Light air automatically changes over to set value by time or piping tem-
perature at thermostat ON.
The fan is to stop during defrosting.
Fan is to run for 1 minute after stopping to exhaust residual heat (only
in heating).
Ultra low-speed operation for 5 minutes after SW ON or until piping
temperature becomes 35°C, low speed operation for 2 minutes there-
after, and then set notch is commenced. (Hot adjust control)
When the heat source unit is being cooled and the refrigerant is rest-
ing, warming up operation is performed for at least 35 minutes to warm
the compressor.
During this time, only the fan operates.
System is being driven.
Operate remote controller again after "HO" disappear.
After a stop of cooling operation, unit continues to operate drain pump
for three minutes and then stops it.
Unit continues to operate drain pump if drainage is generated, even
during a stop.
31