Possible Problems And Solutions - Mitsubishi Electric HP120TNU-A Service Handbook

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

Possible Problems and Solutions

Malfunction
mode
Microcomput- Disconnect the control board connector and connect the
er driver circuit check LED as shown in the figure below.
failure
resistance : 0.25W 1k
LED : DC15V 20mA or more
When the main power is turned on, the indoor unit circuit
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.
LEV mecha- If the LEV is locked, the drive motor runs idle, and makes a
nism is locked small clicking sound.
When the valve makes a closing and opening sound, the
valve has a problem.
Disconnected Measure resistance between the coils (red - white, red -or-
or short-circuit- ange, red - yellow, red - blue) using a tester. They are nor-
ed LEV motor mal if resistance is 100 ± 10%.
coil
Measure resistance between the coils (red - white, red -or-
ange, brown - yellow, brown - blue) using a tester. They are
normal if resistance is 150 ± 3%.
Measure the resistance between coils (red - white, red - or-
ange, brown - yellow, brown - blue) with a tester. When the
resistance is in the range of 46 ± 3%, the LEV is normal.
Incomple seal- When checking the refrigerant leak from the indoor LEV,
ing run the target indoor unit in the fan mode, and the other in-
(leak from the door units in the cooling mode. Then, check the liquid tem-
valve) perature (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 temper-
ature 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 1 Check for loose pins on the connector and check the
connections in . colors of the lead wires visually
the connector
2 Disconnect the control board's connector and conduct a
or faulty con-
. continuity check using a tester.
tact
HWE18220_GB
Judgment method
6
5
4
3
2
1
1 k LED
Thermistor
(liquid piping
temperature detection)
Linear Expansion Valve
Remedy
When the drive circuit Indoor unit,
has a problem, replace Outdoor unit
the control board. and BC control-
ler
Replace the LEV. Indoor unit,
Outdoor unit
and BC control-
ler
Replace the LEV coils. Outdoor unit
(LEV2a,
LEV2b, LEV2d)
and BC control-
ler (LEV3 (G1,
GA1, HA1, KB
type), LEV1
(G1 type))
Replace the LEV coils. Indoor unit and
BC controller
(LEV1 (GA1,
HA1, J, JA, KA
type), LEV3 (J,
JA, KA type))
Replace the LEV coils. Outdoor (LEV1,
LEV4, LEV9)
If there is a large Indoor unit
amount of leakage, re-
place the LEV.
Check the continuity at Indoor unit,
the points where an er- Outdoor unit
ror occurs. and BC control-
ler
LEV
27
chapter 8 -