Mitsubishi Electric PUHY-200YMF-B Service Handbook page 100

Judgment Methods and Likely Failure Mode
Caution:
The specifications of the outdoor unit (outdoor LEV) and outdoor units (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.
Failure Mode
1 Disconnect the control board connector and connect
Microcomputer
Driver Circuit the check LED as shown in the figure below.
Failure
When the base power supply is turned on, the indoor LEV
outputs pulse signals for 10 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
LEV mechanism
is locked. load and a small clicking sound is generated.
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%.
Fully Closed 1 If you are checking the indoor unit's LEV, operate the
Failure (valve indoor unit's blower and the other indoor units in the
leaks) cooling mode, then check the piping temperatures
(liquid pipe temperatures) of the indoor units by the
operation monitor through the outdoor 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 tempera-
1 Check for pins not fully inserted on the connector and
Faulty wire
connections in check the colors of the lead wires visually.
2 Disconnect the control board's connector and conduct
the connector or
faulty contact. a continuity check using a tester.
Judgment Method
ture is considerably low compared
Thermistor
to the remote control's intake
liquid pipe
temperature display, it can be
(tempera-
judged that there is a fully closed
ture sensor)
failure. In the case of minimal
Linear
leakage, it is not necessary to
Expansion
replace the LEV if there are no
Valve
other effects.
Treatment
In the case of driver circuit
failure, replace the indoor unit's
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.
–98–
Affected LEV
Indoor
Indoor
Outdoor
Indoor
Outdoor
Indoor
Indoor
Outdoor