Mitsubishi Electric PQHY-P200YLM-A Service Handbook page 365

[ IX Troubleshooting ]
(3) Judgment methods and possible failure mode
The specifications of the heat source unit (heat source LEV), indoor unit (indoor LEV),and BC controller (BC controller 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
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
Refer to the Service Handbook that came with CMB-WP**V-GA(B)1 for information about the Hybrid City Multi system.
HWE15060
Judgment method
Disconnect the control board connector and connect
the check LED as shown in the figure below.
LED
1 k
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 heat source unit circuit board
outputs pulse signals to the heat source unit LEV for 17
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
Measure the resistance between coils (red-white, red-
orange, red-yellow, red-blue) with a tester. When the
resistance is in the range of 100ohm ± 10%, the LEV is
normal.
Measure resistance between the coils (red - white, red
-orange, brown - yellow, brown - blue) using a tester.
They are normal if resistance is 46ohm
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%.
Replace the LEV coils.
Replace the LEV coils.
3%.
If there is a large
amount of leakage, re-
place the LEV.
Check the continuity at
the points where an er-
ror occurs.
- 356 -
Remedy Target LEV
Indoor
Heat source
Indoor
Heat source
BC controller
Indoor
BC controller
Heat source
(LEV6,LEV7)
BC controller
Heat source
(LEV1,LEVINV)
Indoor
BC controller
Indoor
Heat source
BC controller
GB