Mitsubishi Electric PURY-P72 Service Handbook page 306

[ IX Troubleshooting ]
4) LEV valve closing and opening operation
Valve closed
Valve open
A
E
B
80 - 100 pulses
(2) Judgment methods and possible failure mode
Malfunction mode
Microcomputer
driver circuit failure
LEV mechanism is
locked
Disconnected or
short-circuited LEV
motor coil
Incomple sealing
(leak from the
valve)
Faulty wire connec-
tions in the connec-
tor or faulty contact
HWE1116D
D
C
Fully open: 1400 pulses
Pulses
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 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.
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.
Normal resistance across the coils (Indoor unit LEV: red-white,
red-orange, brown-yellow, brown-blue; BC controller LEV: red-
white, red-orange, red-yellow, red-blue) as measured with a re-
sistance meter should fall within the following ranges. Indoor unit
LEV = 150 10%; BC controller LEV = 100
Normal resistance across the coils (red-white, red-orange,
brown-yellow, brown-blue) as measured with a resistance meter
should fall within the range of 150
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 fully 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 replace the LEV when there are no effects to other parts.
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 power is turned on, the valve closing signal of 2200 pulses
will be output from the indoor board to LEV to fix the valve position.
It must be fixed at point A .
When the valve operates smoothly, no sound from LEV or no vibration
occurs, however, when the pulses change from E to A in the chart or
the valve is locked, a big sound occurs.
*Whether a sound is generated or not can be determined by
holding a screwdriver against it, then placing your ear against the handle.
6
5
4
3
2
1
10%
10%.
Thermistor
(liquid piping
temperature detection)
- 297 -
Remedy
When the drive circuit has a
problem, replace the control
board.
Replace the LEV.
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.
GB