Linear Expansion Valve Operation; Output Pulse Signal And The Valve Operation - Mitsubishi Electric City Multi Series Technical & Service Manual

<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
OCH610G
Output
The output pulse shifts in above order.
3 4
OFF ON
Notes:
OFF OFF
ON OFF
ON ON
Notes:
C
D
Open
Outdoor unit R410A model : 1400 pulse
Outdoor unit R22 model
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
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.
Linear expansion Motor will idle and make a ticking noise when the motor is
valve mechanism is operated while the linear expansion valve is locked. This tick-
locked. ing sound is the sign of the abnormality.
Short or breakage Measure the resistance between each coil (white-red, yellow-
of the motor coil of brown, orange-red, blue-brown) with a tester. It is normal if
the linear expansion the resistance is in the range of 200' ±10%.
valve
Valve does not close To check the linear expansion valve, operate the indoor unit
completely. in fan mode and at the same time operate other indoor units
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 affecting normal operation.
Wrong connection Check the color of lead wire and missing terminal of the con-
of the connector or nector.
contact failure
• 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.
• 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.
: 2000 pulse
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
is any 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.
33
A in order to define the valve position.
E to A or when the valve is locked,
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.