Mitsubishi Electric PKFY Series Technical & Service Manual page 15

<Output pulse signal and the valve operation>
Output
(Phase)
1
1 ON OFF
2 ON ON
3 OFF ON
4 OFF OFF
Linear expansion valve operation
2
Close
A
E
B
Extra tightning (80~100pulse)
Troubleshooting
3
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 does not close
completely (thermis-
tor leaking).
Wrong connection
of the connector or
contact failure.
OC310B
Output
2 3 4
OFF ON
OFF OFF
ON OFF
ON ON
C
D
Open
2000 pulse
Opening a valve
all the way
Pulse number
Disconnect the connector on the controller board, then con-
nect LED for checking.
1
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 expan-
sion valve is closed completely and if there
Liquid pipe
are some leaking, detecting temperature of
thermistor
the thermistor will go lower. If the detected
Linear
temperature is much lower than the tem-
expansion
valve
perature 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 con-
nector.
Closing a valve : 1 → 2 → 3 → 4 → 1
Opening a valve : 4 → 3 → 2 → 1 → 4
The output pulse shifts in above order.
*1. When linear expansion valve operation stops, all output phase
become OFF.
2. At phase interruption or when phase does not shift in order,
motor does not rotate smoothly and motor locks and vibrates.
* When the switch is turned on, 2200 pulse closing valve signal will
be send till it goes to
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 driver
handle while putting the screw driver to the linear expansion valve.
Check points
6
5
4
3
2
1
LED
15
point in order to define the valve position.
A
to or when the valve is locked,
E A
Countermeasures
Exchange the indoor con-
troller board at drive circuit
failure.
Exchange the linear expan-
sion vale.
Exchange the linear expan-
sion valve.
If large amount of thermis-
tor is leaked, exchange the
linear expansion valve.
Disconnect the connector
at the controller board,
then check the continuity.