Mitsubishi Electric Mr. Slim PUZ-M200YKA2.UK Service Manual page 54

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 cir-
cuit 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
ø1
ON ON OFF
ø2
OFF ON ON
ø3
OFF OFF OFF
ø4
OFF OFF OFF
(2) Linear expansion valve operation
Close
A
B
Extra tightening (about 32 pulse)
OCH775B
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
C
Open
500 pulse
Opening a valve
all the way
Pulse number
Gray
ø4
Orange
ø3
Red
Yellow
ø2
ø1 Black
LEV-A
Connector LEV-A
The output pulse shifts in the following order.
Opening a valve: 8 → 7 → 6 → 5 → 4 → 3 → 2 → 1 → 8
Closing a valve: 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 1
· When linear expansion valve operation stops, all output phases
become OFF.
· When the power is turned on, 700 pulse closing valve signal will
be sent till it goes to
(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 screwdriver to the linear expansion
valve.
54
Outdoor controller board
12 VDC
1
Drive circuit
ø4
2
ø3
3
ø2
4
ø1
5
point in order to define the valve position.
to or when the valve is locked,
to in