Mitsubishi Electric PUMY-P125VMA, Техническое и сервисное руководство

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3
Troubleshooting
Problem Check point Corrective measure
Remove the connector from the controller board and connect diagnostic
LEDs.
Pulses will be issued for 10 seconds when the power is turned on.
It indicates that there is an abnormality in the operating circuit if
any LEDs don't turn on or off.
If the linear expansion valve (indoor unit) or electronic expansion valve
(outdoor unit) becomes locked and the motor is still operating, the motor will
emit a clicking noise and will not function. This clicking noise indicates
an abnormality.
Use an all-purpose electrical meter to measure the resistance between the
different coils (red-white, red-orange, brown-yellow, brown-blue). Normal
resistance is within a range of 150
'
±
10%.
In order to check the linear expansion valve, operate one indoor unit in the
fan mode and another in the cooling mode. Then, use the outdoor multi
controller board to operate the monitor and check the pipe temperature of the
indoor unit (liquid pipe temperature). The linear expansion valve should be
fully closed when the fan is operating. The temperature measured by the
temperature sensor will drop if there is any leakage.
If the measured temperature is significantly lower
than that on the remote controller, this indicates that
the valve is not closed. It is not necessary to replace
the linear expansion valve if the leak of refrigerant
is small and does not cause a malfunction.
1
Check improperly connected connector terminals and the wire colors.
2
Remove the connector on the controller board side and check electrical
conductance
Malfunction in microp-
rocessor operating
circuit
Locked expansion
valve
Short circuit or broken
circuit in expansion
valve motor coil
Valve does no close
completely
Incorrect connection
or connection failure
Replace the indoor unit
controller board or
Replace the outdoor
multi controller board.
Replace the linear expa-
nsion valve or electronic
expansion valve
Replace the linear expa-
nsion valve or electronic
expansion valve
Replace the linear expa-
nsion valve if there is a
major leak of refrigerant.
Continuity check of
wrong part.
6
5
4
3
2
1
1k " LED
Temperature
sensor
<liquid pipe>
Linear expansion valve
From the preceding page.
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