Mitsubishi Electric PURY-EP200 Service Handbook page 276

[ IX Troubleshooting ]
(2) Judgment methods and possible failure mode
Malfunction
mode
Microcomputer
driver circuit fail-
ure
LEV mechanism
is locked
Disconnected or
short-circuited
LEV motor coil
Incomple sealing
(leak from the
valve)
Faulty wire con-
nections in the
connector or
faulty contact
HWE0713A
Judgment method
Disconnect the control board connector and connect
the check LED as shown in the figure below.
1 k LED
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.
If any of the LED remains lit or unlit, the drive circuit is
faulty.
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.
Measure resistance between the coils (red - white, red
-orange, brown - yellow, brown - blue) using a tester.
They are normal if resistance is 150ohm
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.
Thermistor
(liquid piping
temperature detection)
Linear Expansion Valve
1. Check for loose pins 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.
When the drive circuit has a
problem, replace the control
board.
6
5
4
3
2
1
Replace the LEV.
Replace the LEV coils.
10%.
If there is a large amount of
leakage, replace the LEV.
Check the continuity at the
points where an error occurs.
- 267 -
Remedy
GB