Mitsubishi Electric TRANE CITY MULTI TPKFYP004LM140A Technical & Service Manual page 30

<Output pulse signal and the valve operation>
Output
(Phase)
1 2
ON OFF
{1
ON ON
{2
OFF ON
{3
OFF OFF
{4
Linear expansion valve operation
2
Open
Close
A
E
Close
B
Extra tightening (200 pulse)
Troubleshooting
3
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
OCHT715A
Output
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 connect LED for checking.
1k" LED
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) using a tester. 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 leaking, detecting tempera-
ture of the thermistor will go lower. If the detected temperature is
Thermistor
much lower than the temperature indicated in the remote controller,
(Liquid pipe)
it means the valve is not closed all the way. It is not necessary to
Linear
exchange the linear expansion valve, if the leakage is small and
expansion
not affecting normal operation.
valve
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
• 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
• When the valve moves smoothly, there is no noise or vibration
occurring from the linear expansion valves : however, when the
pulse number moves from
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.
Check points
6
5
4
3
2
1
30
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 large amount of refrigerant is leaked,
exchange the linear expansion valve.
Disconnect the connector at the con-
troller board, then check the continuity.