–74–
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 stays on,
there is a problem with the driver circuit.
1 If the LEV is locked up, the drive motor turns with no
load and generates a small clicking sound.
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 When 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 should be fully closed, so if there is
leakage, the temperature sensed
by the thermistor (liquid pipe
temperature sensor) will become
low. If the temperature is consider-
ably lower compared to the remote
control’s intake temperature
display, it can be judged that the
LEV is not fully closed.
In the case of minimal leakage, it is not necessary to
replace the LEV.
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 modes of failure
Caution:
Since the specifications of the outdoor unit (outdoor LEV) and indoor unit (indoor LEV) differ, there are cases where
remedies to be taken also differ. Follow the remedy 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.
Incomplete
closure of the
valve
Faulty wire
connections in
the connector or
faulty contact.
Failure Mode Judgment Method Remedy 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
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