30
31
OCH715
Output
(Phase)
Output
{
1
1
ON
{
2
ON
{
3
OFF
{
4
OFF
2
OFF
ON
ON
OFF
3
OFF
OFF
ON
ON
4
ON
OFF
OFF
ON
<Output pulse signal and the valve operation>
2
Linear expansion valve operation
3
Troubleshooting
D
A
E
B
C
Open
Open
Extra tightening (200 pulse)
Pulse number
2000 pulse
Opening a valve
all the way
Close
Close
V
alv
e position (capacity)
The output pulse shifts in below order.
Closing a valve : 1 → 2 → 3 → 4 → 1
Opening a valve : 4 → 3 → 2 → 1 → 4
• 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 power is turned on, 2200 pulse closing valve signal will
be sent till it goes to point
A
in order to define the valve position.
• When the valve moves smoothly, there is no noise or vibration
occurring from the linear expansion valves : however, when the
pulse number moves from
E
to
A
or when the valve is locked,
more noise can be heard than in a normal situation.
• Noise can be detected by placing the ear against the screw driver
handle while putting the screw driver tip to the linear expansion
valve.
6
5
4
3
2
1
LED
1k
"
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 tempera-
ture <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 there is any leaking, detecting tempera-
ture of the thermistor will go lower. If the detected temperature is
much lower than 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 affecting normal operation.
Thermistor
(Liquid pipe)
Linear
expansion
valve
Symptom
Check points
Countermeasures
Operation circuit failure of the
micro- processor
Disconnect the connector on the controller board, then connect LED for checking.
When power is turned on, pulse signals will output for 10 seconds. There must be
some defects in the operation circuit if the LED does not light while the signals are
output or keeps lighting even after the signals stop.
Exchange the indoor controller board at
drive circuit failure.
Linear expansion valve mecha-
nism is locked.
Motor will idle and make a ticking noise when the motor is operated while the linear
expansion valve is locked. This ticking sound is the sign of the abnormality.
Exchange the linear expansion valve.
Short or breakage of the motor
coil of the linear expansion valve
Measure the resistance between each coil (white-red, yellow-brown, orange-red, blue-
brown) using a tester. It is normal if the resistance is in the range of 200
"
±10%.
Exchange the linear expansion valve.
Valve does not close completely.
If large amount of refrigerant is leaked,
exchange the linear expansion valve.
Wrong connection of the connec-
tor or contact failure
Check the color of lead wire and missing terminal of the connector.
Disconnect the connector at the con-
troller board, then check the continuity.
