Checking The Outdoor Fan Motor; Checking The Solenoid Coil; Checking The Power Supply; Checking The Rush Current Control Circuit - Mitsubishi Electric MXZ-18NV Service Manual

H Checking the outdoor fan motor
The outdoor fan motor remains stopped.
<MXZ-18NV>
Disconnect CN63 TAB91
and outdoor electronic
control P.C.board.
Disconnect the connector
between the compressor
and the transistor module.
<MXZ-32NV>
Disconnect the relay
connector. Disconnect t
he connector (lead wire)
between the compressor
and the IPM board.
I Checking the solenoid coil (Only MXZ-32NV)
Poor heating/cooling. The compressor stops frequently.
•First measure the resistance of the reversing valve coil to check the integrity.
•If connector CN913 is not connected or the sorenoid coil is open, voltage occurs
between terminals even when the control is OFF.
Disconnect the lead wire
between compressor
and IPM board.
Turn on power to the
indoor unit and the
outdoor unit, and press
the emergency switch
for heating operation.

(Checking the power supply)

J Checking the power supply
The inverter does not operate.
Turn on power
to the outdoor
unit.
Yes
Is there voltage
of 220 to 240V AC
the power terminal
block?
No
Check the powerline
K Checking the rush current control circuit
The outdoor unit does not operate at all or
stops in short time due to over current.
Is the current limiting
resistor disconnected?
(It has 10 , if normal.)
Yes
Replace the current
limiting resistor.
Check other main circuit parts at the same time when you replace the current limiting resistor.
• First, measure the resistance of the 4-way valve
Turn on power to the indoor
unit and the outdoor unit,
the press the emergency
switch for cooling or heating
operation.
Three minutes after
power-on, check the
voltage between terminals
at the relay connector.
Three minutes after
power-on, check the v
oltage between
pin3 and pin4 or CN913
on the noise filter board.
Is there voltage of 220
to 240V AC ?
Is there voltage
of 310 to 340V AC across
the the smoothing capacitor?
Yes
Activate the indoor
unit emergency
operation.
No
Turn on power
to the outdoor
unit.
coil to check the integrity.
No
<MXZ-18NV>
Is there voltage of
220 - 240V AC
between CN63 2 and
3 or 2 and 5?
<MXZ-32NV>
Is there voltage of
220 - 240V AC
between pin2 and any
of pin3, 4, 5, and 6?
No
Yes
No Main electric parts
defective in the
circuit.
Three minutes later
does the serial signal
error occur?
No
Refer to the serial
signal check method.
Does LED light
up?
Yes
Is the rush current liming
relay functioning properly?
(It should close one second
after the outdoor unit power-on,
if normal.)
No
Outdoor controller board or
rush current liming resistor defective.
Outdoor control board or
outdoor relay board defective.
•Outdoor fan motor
lead wire defective.
Yes
•Poor contact for
connector
•Outdoor fan motor
damaged.
Outdoor control board or
outdoor relay board defective.
•Sorenoid coil
lead wire defective.
•Poor contact of
connector
•Sorenoid coil
damaged.
Outdoor or indoor
Yes
controller board
defective.
Main components in the
No
circuit or outdoor
controller board
defective.
Yes
Other main components
in the circuit or
compressor defective.
47