Mitsubishi Electric PUHY-P250YJM-A, Service Manual

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[
X
Troubleshooting ]
- 199 -
HWE10190 GB
(3) Judgment methods and possible failure mode
The specifications of the outdoor unit (outdoor LEV) and the indoor unit (indoor LEV) differ.Therefore, remedies for each failure
may vary. Check the remedy specified for the appropriate LEV as indicated in the right column.
Malfunction
mode
Judgment method Remedy Target
LEV
Microcomputer
driver circuit fail-
ure
Disconnect the control board connector and connect
the check LED as shown in the figure below.
resistance : 0.25W 1k
LED : DC15V 20mA or more
When the main power is turned on, the indoor unit cir-
cuit board outputs pulse signals to the indoor unit LEV
for 10 seconds, and the outdoor unit circuit board out-
puts pulse signals to the outdoor unit LEV for 17 sec-
onds.
If any of the LED remains lit or unlit, the drive circuit is
faulty.
When the drive circuit has a
problem, replace the control
board.
Indoor
Outdoor
LEV mechanism
is locked
If the LEV is locked, the drive motor runs idle, and
makes a small clicking sound.
When the valve makes a closing and opening sound,
the valve has a problem.
Replace the LEV. Indoor
Outdoor
Disconnected or
short-circuited
LEV motor coil
Measure the resistance between coils (indoor unit LEV:
red-white, red-orange, brown-yellow, brown-blue; out-
door unit LEV: red-white, red-orange, red-yellow, red-
blue) with a tester. When the resistance is in the range
of 150 Ω 10%, the LEV is normal.
Replace the LEV coils. Indoor
Outdoor
(LEV2)
Measure resistance between the coils (red - white, red
-orange, brown - yellow, brown - blue) using a tester.
They are normal if resistance is 46ohm 3%.
Replace the LEV coils. Outdoor
(LEV1)
Incomple sealing
(leak from the
valve)
When checking the refrigerant leak from the indoor
LEV, run the target indoor unit in the fan mode, and the
other indoor units in the cooling mode. Then, check the
liquid temperature (TH22) with the self-diagnosis LED.
When the unit is running in the fan mode, the LEV is ful-
ly closed, and the temperature detected by the thermis-
tor is not low. If there is a leak, however, the
temperature will be low. If the temperature is extremely
low compared with the inlet temperature displayed on
the remote controller, the LEV is not properly sealed,
however, if there is a little leak, it is not necessary to re-
place the LEV when there are no effects to other parts.
If there is a large amount of
leakage, replace the LEV.
Indoor
Faulty wire con-
nections in the
connector or
faulty contact
1. Check for loose pins on the connector and check
the colors of the lead wires visually
Check the continuity at the
points where an error occurs.
Indoor
Outdoor
2. Disconnect the control board's connector and
conduct a continuity check using a tester.
6
5
4
3
2
1
1 k LED
Thermistor
(liquid piping
temperature detection)
Linear Expansion Valve
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