Mitsubishi Electric PUHY-P200 Service Handbook page 142

(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.
Failure mode
Microcomputer 1. Disconnect the control board connector and connect the
driver circuit 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, 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.
LEV mechanism is 1. If the LEV is locked up, the drive motor turns with no
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 coils Measure the resistance between the coils (red - white, red -
have a disconnect- orange, brown - yellow, brown - blue) using a tester. They
are normal if the resistance is within 150Ω ± 10%.
ed 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 ± 10%.
Fully closed failure 1. If you are checking the indoor unit's LEV, operate the
(valve leaks) 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
Faulty wire connec- 1. Check for pins not fully inserted on the connector and
tions in the connec- check the colors of the lead wires visually
tor or faulty contact. 2. Disconnect the control board's connector and conduct a
continuity check using a tester.
Judgment method
6
5
4
3
2
1
1kΩ
LED
become low. If the temperature
is considerably low compared
Thermistor liquid
to the remote control's intake
pipe (temperature
sensor)
temperature display, it can be
judged that there is not a fully
closed failure. In the case of
Linear expansion
minimal leakage, it is not nec-
valve
essary to replace the LEV if
there are no other effects.
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.
- 140 -
Treatment Affected LEV
Indoor
Outdoor
Indoor
Outdoor
Indoor
Outdoor
Indoor
Indoor
Outdoor