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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
outputs pulse signals for 17 seconds, and BC controller
outputs pulse signals for 10-20 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 150Ω ± 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 46Ω ± 3%.
1 If you are checking the indoor unit’s LEV, operate the
indoor unit’s blower and the other indoor units in the
cooling mode, then check the piping temperatures
(liquid pipe temperatures) of the indoor units by the
operation monitor 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 a fully
closed failure. In the case of
minimal leakage, it is not necessary 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.
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.
Microcomputer
driver circuit
failure
LEV mechanism
is locked.
The LEV motor
coils have a
disconnected
wire or is shorted.
Fully closed
failure (valve
leaks)
Faulty wire
connections in
the connector or
faulty contact.
Failure Mode Judgment Method Treatment Affected LEV
Thermistor
liquid pipe
(tempera-
ture sensor)
Linear
Expansion
Valve
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
leakage, replace the LEV.
Check the continuity at the
places where trouble is found.
Indoor
BC controller
Outdoor
Indoor
BC controller
Outdoor
Indoor
BC controller
Outdoor
Indoor
BC controller
Indoor
BC controller
Outdoor
Indoor, BC controller
Outdoor