Fujitsu AB12 Service Manual page 121

3. Abnormal sound is heard from the indoor unit.
LED display
Indoor Outdoor Remote
unit unit controller
Body PCB LED
LCD
LED 1 to 6
Normal
Normal Normal
display
display display
Symptom that
Cause
can occur other
than title
RB unit solenoid valve faulty.
SVb1, 2 solenoid valve faulty.
Indoor electronic expansion
valve opening faulty.
Indoor unit
Indoor electronic expansion
other than the valve opening faulty.
relevant indoor
Fully open (open excessively)
unit does not
Cooling operations performed.
perform cooling.
Indoor unit Indoor unit electronic expansion
other than the valve opening faulty.
relevant indoor Fully open (open excessively)
unit does not Cooling stopped
perform cooling.
Indoor unit heat
exchanger icing.
Indoor unit Indoor unit electronic expansion
other than
valve opening faulty.
relevant indoor
Full open (open excessively)
unit does not
Heating operation
perform heating.
Indoor unit electronic expansion
valve opening faulty.
Full open (open excessively)
Heating stopped.
Outdoor cool/heat switching
System does
4-way valve (4WV1) faulty.
not cool/heat
(Cooling/heating pump type only)
Outdoor heat exchanger
switching 4-way valve (4WV2,
4WV3, 4WV4) or solenoid valve
(SV7, SV8) faulty.
Installed piping is unsuitable.
Liquid piping diameter is
incorrect.
Check method
(Error state check method)
When heating operation starts,
a voltage (AC220V) is applied to
indoor unit control PCB CN6
(across terminals 3-4), but 3
minutes later a loud refrigerant
rushing sound is generated from
the RB unit.
The area (heat exchanger) near
the air diffuser is not cooled even
after several minutes have
elapsed since the relevant
indoor unit was stopped.
(Gas pipe is cold.)
The area (heat exchanger) near
the air diffuser of the stopped
relevant indoor unit is cold.
(Gas pipe is cold.)
When the relevant indoor unit
performs the heating operation
or another indoor unit performs
the heating operation, the indoor
unit discharge temperature does
not become high and the high
pressure becomes low.
When the relevant indoor unit or
another indoor unit performs the
heating operation, the indoor unit
discharge temperature does not
become high and the high
pressure become low.
28 dia. gas piping temperature
corresponding to 4WV1
energized state(cooling,
de-energized, heating,
energized(AC220V) is abnormal
(cooling : cold, heating : hot).
Check the heat exchange
operation capacity at the outdoor
control PCB LED.
The energized state (AC220V)
of the heat exchange 4-way valve
and solenoid valve corresponding
to it is abnormal. (Separate
sheet 1)
Check the indoor unit capacity
and pipe diameter.
– 121–
Remarks
Coil resistance : 1200~1500
Coil resistance (red-white,
red-orange, brown-blue,
brown-yellow) : 100~200
When the electronic expansion
valve is open excessively, other
indoor units may not operate at
full capacity or a loud refrigerant
rushing sound may be generated.
When the electronic expansion
valve opens, the indoor heat
exchanger may ice while
stopped and water leakage or
other trouble may occur.
4-way valve coil resistance
: 1200~1500
When a 4-way valve or solenoid
valve is faulty, the high pressure
rises during the cooling operation
and the low pressure drops
during the heating operation.
Coil resistance : 1200~1500
When the diameter is large, a
refrigerant rushing sound will be
generated and when the
diameter is small, capacity will
be insufficient.