(3) Judgment methods and likely failure mode
Caution:
The specifications of the outdoor unit (outdoor LEV) and indoor unit (indoor LEV) differ. For this reason, there are cases
where the treatment contents differ, so follow the treatment specified for the appropriate LEV as indicated in the right
column.
In the case of driver circuit failure,
replace the control board.
Replace the LEV.
Replace the LEV coils.
Replace the LEV coils.
If there is a large amount of leak-
age, replace the LEV.
Check the continuity at the
places where trouble is found.
Failure mode
Judgment method
Treatment
Affected LEV
Microcomputer
driver circuit
failure
LEV mechanism is
locked
The LEV motor coils
have a disconnect-
ed wire or is shorted
Fully closed failure
(valve leaks)
Faulty wire connec-
tions in the connec-
tor or faulty contact.
1. Disconnect the control board connector and connect the
check LED as shown in the figure below.
When the base power supply is turned on, the indoor LEV
outputs pulse signals for 10 seconds, the outdoor LEV out-
puts pulse signals for 17 seconds.
If the LED does not light up, or lights up and remains on, the
driver circuit is abnormal.
1. If the LEV is locked up, the drive motor turns with no
load and a small clicking sound is generated.
Generation of this sound when the LEV is fully closed or
fully open is abnormal.
Measure the resistance between the coils (red - white, red -
orange, brown - yellow, brown - blue) using a tester. They
are normal if the resistance is within 150
Ω
±
10%.
Measure the resistance between the coils (gray - orange,
gray - red, gray - yellow, gray - black) using a tester. They
are normal if the resistance is within 46
Ω
±
10%.
1. If you are checking the indoor unit’s LEV, operate the
indoor unit’s blower and the other indoor units in the cool-
ing mode, then check the piping temperatures (liquid pipe
temperatures) of the indoor units by the operation moni-
tor through the heat source unit’s control board. When
the fan is running, the linear expansion valve is fully
closed, so if there is leakage, the temperature sensed
by the thermistor (liquid pipe temperature sensor) will
become low. If the temperature
is considerably low compared
to the remote control’s intake
temperature display, it can be
judged that there is not a fully
closed failure. In the case of
minimal leakage, it is not nec-
essary to replace the LEV if
there are no other effects.
1. Check for pins not fully inserted on the connector and
check the colors of the lead wires visually
2. Disconnect the control board’s connector and conduct a
continuity check using a tester.
Indoor
Outdoor
Indoor
Outdoor
Indoor
Outdoor
Indoor
Indoor
Outdoor
6
5
4
3
2
1
1k
Ω
LED
Thermistor liquid
pipe (temperature
sensor)
Linear expansion
valve
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