Mitsubishi City Multi PURY-P400 Service Handbook page 75

• 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.
Failure Mode
Microcomputer
1 Disconnect the control board connector and connect
driver circuit
the check LED as shown in the figure below.
failure
Indoor, BC controller
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.
LEV mechanism
1 If the LEV is locked up, the drive motor turns with no
is locked.
load and generates a small clicking sound.
Generation of this sound when the LEV is fully closed
or fully open is abnormal.
The LEV motor
Measure the resistance between the coils (red - white, red
coils have a
- orange, brown - yellow, brown - blue) using a tester. They
are normal if the resistance is within 150Ω ± 10%.
disconnected wire
or is shorted.
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%.
Incomplete
1 When checking the indoor unit's LEV, operate the
closure of the
indoor unit's blower and the other indoor units in the
valve
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
In the case of minimal leakage, it is not necessary to
replace the LEV.
Faulty wire
1 Check for pins not fully inserted on the connector and
connections in
check the colors of the lead wires visually.
the connector or
2 Disconnect the control board's connector and conduct
faulty contact.
a continuity check using a tester.
Judgment Method
Outdoor
leakage, the temperature sensed
Thermistor
by the thermistor (liquid pipe
liquid pipe
temperature sensor) will become
(tempera-
low. If the temperature is consider-
ture sensor)
ably lower compared to the remote
Linear
control's intake temperature
Expansion
display, it can be judged that the
Valve
LEV is not fully closed.
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.
–74–
Remedy Affected LEV
Indoor
BC controller
Outdoor
Indoor
BC controller
Outdoor
Indoor
BC controller
Outdoor
Indoor
BC controller
Indoor
BC controller
Outdoor