Troubleshooting Principal Parts - Mitsubishi Electric CMB-WM108V-AA Service Handbook

[ VIII Troubleshooting ]

[4] Troubleshooting Principal Parts

LEV
-1- 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)
LEV
Blue
4
Red
6
M
Yellow
2
5
1
White
Orange
2) Pulse signal output and valve operation
Output
(phase)
number
1
1 ON
2 ON
3 OFF
4 OFF
3) LEV valve closing and opening operation
Valve closed
A
E
Extra tightening
HWE1708A
ø4
ø3
ø2
ø1
Output state
2 3
OFF OFF
ON OFF
ON ON
OFF ON
D
Valve open
Pulses
B
Brown
Blue
Orange
Yellow
White
Connection
(CNLEV1,2,3)
Output pulses change in the following orders when the
Valve is closed; 1
4
Valve is open;
ON
*1. When the LEV opening angle does not change,
OFF
all the output phases will be off.
OFF
*2. When the output is open phase or remains ON,
ON
the motor cannot run smoothly, and rattles and vibrates.
C
* Upon power on, the HBC controller circuit board sends 3200 Hz pulse closing
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.
After the valve position has been adjusted to the position as indicated by A in
the diagram below, the HBC controller circuit board sends a 41-pulse signal
to bring the LEV opening to the position as indicated by B in the diagram below.
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.
Fully open *1
. 3000 pulses (HBC controller LEV1, 2, 3)
- 186 -
Control board
DC12V
6
5
Drive circuit
ø4
4
ø3
3
ø2
2
ø1
1
2 3 4 1
4 3 2 1 4
GB