Mitsubishi Electric City Multi CMB-WP108V-G, Service Manual

Page: 221 / 301

[
IX
Troubleshooting ]
- 212 - HWE1113B GB
LEV
-5- LEV
LEV operation
HBC controller LEVI, 2, and 3 (linear expansion valves) are driven by the pulse signal from the control board and are controlled
by a stepping motor.
(1) HBC controller LEV
The valve opening changes according to the number of pulses.
1) Control boards and the LEV (HBC controller LEV1, 2, 3)
2) Pulse signal output and valve operation
3) LEV valve closing and opening operation
ø4
ø3
ø 2
ø 1
ø4
ø3
ø 2
ø 1
Control board
Drive c ir c uit
LEV
M
5
2
1
3
4
6
DC12V
Brown
Blue
O range
Yellow
W h ite
O range W h ite
Blue
Yellow
Red
6
5
4
3
2
1
O utput state O utput
(p h ase)
number
1 2 3 4
1 O N O FF O FF O N
2 O N O N O FF O FF
3 O FF O N O N O FF
4 O FF O FF O N O N
O utput pulses ch ange in t h e f ollowing orders w h en t h e
Valve is c losed ; 1 2 3 4 1
Valve is open ; 4 3 2 1 4
* 1. W h en t h e LEV opening angle does not ch ange ,
all t h e output p h ases will be o ff .
* 2. W h en t h e output is open p h ase or remains O N ,
t h e motor c annot run smoot h l y, and rattles and vibrates.
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.
*1 The LEV opening may become greater depending on the operation status.
* Upon power on, the HBC controller circuit board sends 3200 Hz pulse
signals to the LEVs (HBC controller LEV 1, 2, and 3) to determine the valve
position and bring the valve to the position as indicated by A in the diagram.
.3000 pulses (HBC controller LEV1, 2, 3)
V
a
lve opening (refrigerant flow rate)
Valve closed
Valve open
E
B
80 - 100 pulses
Pulses
Fully open *1
A
C
D