Linear Expansion Valve - Mitsubishi Electric PUHZ-FRP71VHA Service Manual

Linear expansion valve

(1) Operation summary of the linear expansion valve
• Linear expansion valve opens/closes 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
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 tightening (about 32 pulse)
OCH544
Output
5 6 7 8
4
OFF OFF OFF OFF ON
ON OFF OFF OFF OFF
ON ON ON OFF OFF
OFF
OFF ON ON ON
Open
500 pulse
Opening a valve
all the way
Pulse number
4
3
2
1
Connector LEV-A
LEV-B
LEV-C
Opening a valve : 8 → 7 → 6 → 5 → 4 → 3 → 2 → 1 → 8
Closing a valve : 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 1
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
A
(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
more sound can 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 driv-
er handle while putting the screw driver to the linear expansion
valve.
51
Outdoor controller board
DC12V
1
Gray
Drive circuit
Orange 2
Red 3
Yellow 4
Black 5
point in order to define the valve position.
to or when the valve is locked,
B A
4
3
2
1
to in
B A