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<Output pulse signal and the valve operation>
Output
(Phase)
1
2
ø1
ON
OFF
ø2
ON
ON
ø3
OFF
ON
ø4
OFF
OFF
2 Linear expansion valve operation
Open
Close
A
E
Close
B
Extra tightening (200~800 pulse)
3 Troubleshooting
Symptom
Operation circuit failure of the
micro processor
Linear expansion valve mecha-
nism is locked.
Short or breakage of the motor
coil of the linear expansion valve
Valve does not close completely.
Wrong connection of the connec-
tor or contact failure
OCHT746A
Output
3
4
OFF
ON
OFF
OFF
ON
OFF
ON
ON
C
D
Open
Outdoor unit R410A model: 1400 pulse
Outdoor unit R22 model: 2000 pulse
Opening a valve
all the way
Pulse number
Disconnect the connector on the controller board, then connect LED for checking.
1k"
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.
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.
Measure the resistance between each coil (white-red, yellow-brown, orange-red,
blue-brown) with a multimeter. It is normal if the resistance is in the range of 200 '
±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 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
leakage, detecting temperature of the thermistor will go lower.
Thermistor
(Liquid pipe)
If the detected temperature is much lower than the temperature
Linear
indicated in the remote controller, it means the valve is not closed
expansion
all the way. It is not necessary to exchange the linear expansion
valve
valve, if the leakage is small and not affecting normal operation.
Check the color of lead wire and missing terminal of the connector.
The output pulse shifts in below order.
Closing a valve: 1 → 2 → 3 → 4 → 1
Opening a valve: 4 → 3 → 2 → 1 → 4
Notes:
• When linear expansion valve operation stops, all output phases
become OFF.
• At phase interruption or when phase does not shift in order, motor
does not rotate smoothly and motor will lock and vibrate.
Notes:
• When the power is turned on, 2200 pulse closing valve signal will
be sent till it goes to point
• When the valve moves smoothly, there is no sound or vibration
occurring from the linear expansion valves, however, when the
pulse number moves from
more sound can be heard than in a normal situation.
• Sound can be detected by placing the ear against the screw driver
handle while putting the screw driver tip to the linear expansion
valve.
Checkpoints
6
5
4
3
2
1
LED
33
in order to define the valve position.
A
to
or when the valve is locked,
E
A
Countermeasures
Exchange the indoor controller board at
drive circuit failure.
Exchange the linear expansion valve.
Exchange the linear expansion valve.
If a large amount of refrigerant is leaked,
exchange the linear expansion valve.
Disconnect the connector at the controller
board, then check for continuity.
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