Mitsubishi Electric PMFY Series Technical & Service Manual page 24

<Output pulse signal and the valve operation>
Output
(Phase)
1 2
{1
ON OFF
{2
ON ON
{3
OFF ON
{4
OFF OFF
2
Linear expansion valve operation
Close
A
E
B
Extra tightening (80~100pulse)
3
Troubleshooting
OC307E
Output
3 4
OFF ON
OFF OFF
ON OFF
ON ON
C
D
Open
2000 pulse
Opening a valve
all the way
Pulse number
Symptom
Operation circuit Disconnect the connector on the controller board, then con-
failure of the micro nect LED for checking.
processor
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.
Linear expansion Motor will idle and make ticking noise when motor is operated
valve mechanism is while the linear expansion valve is locked. This ticking sound
locked. is the sign of the abnormality.
Short or breakage Measure the resistance between the each coil (red-white, red-
of the motor coil of orange, brown-yellow, brown-blue) with a tester. It is normal if
the resistance is in the range of 200 " ± 10%.
the linear expansion
valve
Valve does not close To check the linear expansion valve, operate the indoor unit
completely (thermis- in fan mode and at the same time operate other indoor units
tor leaking). in cooling mode, then check the pipe temperature <liquid
Thermistor
(Liquid pipe)
Linear
expansion
valve
It is not necessary to exchange the linear expansion valve, if
the leakage is small and not making any trouble.
Wrong connection Check the color of lead wire and missing terminal of the con-
of the connector or nector.
contact failure
Closing a valve : 1 → 2 → 3 → 4 → 1
Opening a valve : 4 → 3 → 2 → 1 → 4
The output pulse shifts in above order.
• When linear expansion valve operation stops, all output phase
become OFF.
• At phase interruption or when phase does not shift in order, motor
does not rotate smoothly and motor will lock and vibrate.
• When the switch is turned on, 2200 pulse closing valve signal will
be send till it goes to A point in order to define the valve position.
• When the valve move smoothly, there is no sound or vibration occur-
ring from the linear expansion valve : however, when the pulse
number moves from E to A or when the valve is locked, more
sound can be heard than normal situation.
• Sound 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
1k LED
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
are some leaking, detecting temperature of
the thermistor will go lower. If the detected
temperature is much lower than the tem-
perature indicated in the remote controller,
it means the valve is not closed all the way.
24
Countermeasures
Exchange the indoor con-
troller board at drive circuit
failure.
Exchange the linear expan-
sion valve.
Exchange the linear expan-
sion valve.
If large amount of refriger-
ant is leaked, exchange
the linear expansion valve.
Disconnect the connector
at the controller board,
then check the continuity.