Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook

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[6-4 The Following Symptoms Are Normal ]
6 -
chapter 6 HWE18240_GB
6 Test Run
6-4 The Following Symptoms Are Normal
Symptoms
Remote controller
display
Cause
The indoor unit does not start
after starting cooling (heating)
operation. "Cooling (heating)"
icon blinks on the
display.
The unit cannot perform a heating (cooling) operation when other indoor
units on the same refrigerant system, are performing a cooling (heating)
operation.
The auto vane adjusts its posi-
tion by itself.
Normal display
After an hour of cooling operation with the auto vane in the vertical posi-
tion, the vane may automatically move into the horizontal position.
Louver blades will automatically move into the horizontal position while
the unit is in the defrost mode, pre-heating stand-by mode, or when the
thermostat triggers unit off.
The fan speed changes dur-
ing heating.
Normal display
Very Low fan speed when "Thermo-OFF.' Changes from Very Low to pre-
set fan speed when "Thermo-ON" depending on pipe temperature.
The fan stops during heating
operation.
Defrost
The fan remains stopped during defrost operation.
The fan keeps running after
the unit has stopped.
Unlit
When the auxiliary heater is turned on, the fan operates for one minute
after stopping to dissipate heat.
The fan speed does not reach
the set speed when operation
switch is turned on.
STAND BY
The fan operates at extra low speed for 5 minutes after it is turned on or
until the pipe temperature reaches 35°C[95°F], then it operates at low
speed for 2 minutes, and finally it operates at the set speed.
(Pre-heating stand-by)
When the main power is
turned on, the display shown
on the right appears on the in-
door unit remote controller for
5 minutes.
"HO" or "PLEASE
WAIT" icons blink
on the display.
The system is starting up. Wait until the blinking display of "HO" or
"PLEASE WAIT" go off.
The drain pump keeps run-
ning after the unit has
stopped.
Unlit
The drain pump stays in operation for three minutes after the unit in the
cooling mode is stopped.
The drain pump is running
while the unit is stopped.
Unlit
When drain water is detected, the drain pump goes into operation even
while the unit is stopped.
Indoor unit makes noise dur-
ing cooling/heating change-
over.
Normal display
This noise is made when the refrigerant circuit is reversed and is normal.
Sound of the refrigerant flow is
heard from the indoor unit im-
mediately after starting opera-
tion.
Normal display
This is caused by the transient instability of the refrigerant flow and is nor-
mal.
Warm air sometimes comes
out of the indoor units that are
not in the heating mode.
Normal display
This is due to the fact that the LEVs on some of the indoor units are kept
slightly open to prevent the refrigerant in the indoor units that are not op-
erating in the heating mode from liquefying and accumulating in the com-
pressor. It is part of a normal operation.