Mitsubishi Electric PKA-RP1.6GAL Service Technical Manual page 31

Linear expansion valve
(1) Operation summary of the linear expansion valve.
• Linear expansion valve open/close through stepping motor after receiving the pulse signal from the outdoor controller board.
• Valve position can be changed in proportion to the number of pulse signal.
<Connection between the outdoor controller board and the linear expansion valve>
LEV
3
2
M
5
1
6 4
<Output pulse signal and the valve operation>
Output
(Phase)
1 2 3
[1
ON ON OFF
[2
OFF ON ON
[3
OFF OFF OFF
[4
OFF OFF OFF
(2) Linear expansion valve operation
Open
Close
A
Close
B
Extra tightning (about 200 pulse)
Output
4 5 6 7 8
OFF OFF OFF OFF ON
OFF OFF OFF OFF
ON
ON ON ON OFF OFF
OFF ON ON ON
OFF
C
Open
500 pulse
Opening a valv
all the way
Pulse number
Red
Brown
[4
Blue
[3
Orange
Yellow
[2
White
[1
Connector LEV-A
LEV-B
Opening a valve : 8 7
Closing a valve : 1 2 3
The output pulse shifts in above order.
1. When linear expansion valve operation stops, all output phase
become OFF.
When the switch is turned on, 700 pulse closing valve signal will
be sent till it goes to point
(The pulse signal is being sent for about 20 seconds.)
When the valve moves smoothly, there is no noise or vibration
occurring from the linear expansion valve : however, when the
pulse number moves from
more noise can be heard than normal situation.
No noise is heard when the pulse number moves from
case coil is burn out or motor is locked by open-phase.
Noise can be detected by placing the ear against the screw dri-
ver handle while putting the screw driver to the linear expansion
valve.
31
Outdoor controller board
DC12V
1
Drive circuit
2
[4
3
[3
4
[2
5
[1
6
6 5 4 3 2 1
4 5 6 7 8 1
in order to define the valve position.
A
to or when the valve is locked,
B A
8
to in
B A