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Possible Problems And Solutions - Mitsubishi Electric PURY-HP72 Service Handbook

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[8-8 Troubleshooting LEV Problems ]
8-8-2

Possible Problems and Solutions

Malfunction
mode
Microcomputer
Disconnect the control board connector and connect the check LED
driver circuit fail-
as shown in the figure below.
ure
resistance : 0.25W 1kΩ
LED : DC15V 20mA or more
When the main power is turned on, the indoor unit circuit board out-
puts pulse signals to the indoor unit LEV for 10 seconds.
If any of the LED remains lit or unlit, the drive circuit is faulty.
LEV mechanism
If the LEV is locked, the drive motor runs idle, and makes a small
is locked
clicking sound.
When the valve makes a closing and opening sound, the valve has
a problem.
Disconnected or
If the resistance between the coils on indoor and BC controller LEVs
short-circuited
(Indoor unit LEV: red-white, red-orange, brown-yellow, and brown-
LEV motor coil
blue; BC controller LEV: red-white, red-orange, red-yellow, and red-
blue) as measured with a tester is in the range of 150 Ω ±10% (in-
door unit LEV) or , 100 Ω ±10% (BC controller LEV), the LEVs are
normal.
Measure resistance between the coils (red - white, red -orange,
brown - yellow, brown - blue) using a tester. They are normal if re-
sistance is 150Ω ± 3%.
Incomple sealing
When checking the refrigerant leak from the indoor LEV, run the tar-
(leak from the
get indoor unit in the fan mode, and the other indoor units in the cool-
valve)
ing mode. Then, check the liquid temperature (TH22) with the self-
diagnosis LED. When the unit is running in the fan mode, the LEV is
fully closed, and the temperature detected by the thermistor 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 replace the LEV
when there are no effects to other parts.
Faulty wire con-
1.
nections in the
connector or
2.
faulty contact
HWE13080
Judgment method
LED
1 k
Thermistor
(liquid piping
temperature detection)
Linear Expansion Valve
Check for loose pins on the connector and check the colors of
the lead wires visually
Disconnect the control board's connector and conduct a con-
tinuity check using a tester.
- 275 -
When the drive circuit has a
problem, replace the control
board.
6
5
4
3
2
1
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
points where an error occurs.
Remedy
GB

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