Mitsubishi Electric PKFY Series Technical & Service Manual page 16

<Output pulse signal and the valve operation>
Output
Output
(Phase)
1 2
{1 ON OFF
{2 ON ON
{3 OFF ON
{4 OFF OFF
Linear expansion valve operation
Close
Open
A
E
B
Extra tightning (80~100pulse)
Trouble shooting
Symptom
Operation circuit
failure of the
micro processor.
Linear expansion
valve mechanism
is locked.
Short or breakage of
the motor coil of the
linear expansion
valve.
Valve doesn't
close completely
(thermistor leak-
ing).
Wrong connection
of the connector
or contact failure.
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Closing a valve : 1
3 4
Opening a valve : 4
OFF ON
The output pulse shifts in above order.
OFF OFF
1. When linear expansion valve operation stops, all output phase
become OFF.
ON OFF
2. At phase interruption or when phase does not shift in order,
motor does not rotate smoothly and motor locks and vibrates.
ON ON
D C
When the switch is turned on, 2200 pulse closing valve signal will
be send till it goes to
tion.
When the valve move 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.
Noise can be detected by placing the ear against the screw dri-
2000 pulse
Opening a valve
ver handle while putting the screw driver to the linear expansion
all the way
valve.
Pulse number
Check points
Disconnect the connector on the controller board,
then connect LED for checking.
1T LED
Pulse signal will be sent out for 10 seconds as soon as
the main switch is turned on. If there is LED with lights
on or lights off, it means the operation circuit is abnormal.
Motor will idle and make ticking noise when motor is
operated while the linear expansion valve is locked. This
ticking sound is the sign of the abnormality.
Measure the resistance between the each coil (red-white,
red-orange, brown-yellow, brown-blue) using a tester. It
is normal if the resistance is in the range of 150'+10%.
To check the linear expansion valve, operate the indoor unit
in fan mode and at the same time operate other indoor units
in cooling mode, then check the pipe temperature <liquid
pipe temperature> of the indoor unit by the
outdoor multi controller board operation
monitor. During fan operation, linear
expansion valve is closed completely and if
Liquid pipe
there are some leaking, detecting tempera-
thermistor
ture of the thermistor will go lower. If the
Linear
detected temperature is much lower than
expansion
valve
the temperature indicated in the remote
controller, it means the valve is not closed all the way. It is
not necessary to exchange the linear expansion valve, if the
leakage is small and not making any trouble.
Check the color of lead wire and missing terminal of
the connector.
2 3 4 1
3 2 1 4
⁄
point in order to define the valve posi-
A
to ⁄
E A
Countermeasures
Exchange the indoor
controller board at drive
6
circuit failure.
5
4
3
2
1
Exchange the linear
expansion vale.
Exchange the linear
expansion valve.
If large amount of ther-
mistor is leaked,
exchange the linear
expansion valve.
Disconnect the connec-
tor at the controller
board, then check the
continuity.
16
or when the valve is locked,