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Mitsubishi Electric Ecodan QUHZ-W40VA Service Manual page 21

Air to water heat pump outdoor unit
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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
M
6
1
When the switch is turned on ,550 pulse closing valve signal will be sent till it goes to
A point in order to define the valve position. (The pulse signal is being sent for about 20 seconds.)
<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)
GHH15010
3
2
5
4
Output
5
6
7
8
4
OFF
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
OFF
ON
ON
ON
OFF
OFF
OFF
ON
ON
ON
OFF
Open
500 pulse
Opening a valve
all the way
Pulse number
Red 1
Blue 3
Orange 4
Yellow 5
White 6
Opening a valve : 8
7
Closing a valve : 1
2
The output pulse shifts in above order.
When linear expansion valve operation stops, all output phases
become OFF.
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.
21
Outdoor controller board
12V DC
2
6
5
4
3
2
1
3
4
5
6
7
8
or when the valve is locked, sound can
8
1
to
in

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