Mitsubishi Electric PUHZ-RP250YHA2 Service Manual page 52

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 circuit board.
• Valve position can be changed in proportion to the number of pulse signal.
<Connection between the indoor controller circuit board and the linear expansion valve>
LEV
3
2
M
5
1
4
6
<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
Close
Extra tightning (about 32 pulse)
(RP250)
Output
4 5 6 7 8
OFF OFF OFF OFF ON
OFF OFF OFF OFF
ON
ON ON ON OFF OFF
OFF OFF ON ON ON
Open
500 pulse
Opening a valve
all the way
Pulse number
Red
Brown
4
Blue
3
Orange
Yellow
2
1 White
Connector LEV-A
LEV-B
Opening a valve : 8 7
Closing a valve : 1 2 3
The output pulse shifts in above order.
• 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 in order to define the valve position. (The
pulse signal is being sent for about 20 seconds.)
• When the valve moves smoothly, there is no sound or vibration
occurring from the linear expansion valve ; however, when the pulse
number moves from to
be heard.
No sound is heard when the pulse number moves from
case coil is burnt out or motor is locked by open-phase.
• Sound can be detected by placing the ear against the screw driver
handle while putting the screw driver to the linear expansion valve.
52
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
or when the valve is locked, sound can
8
to in