Mitsubishi Electric MXZ-2B20NA Service Manual page 73

MXZ-5B42NA
Disconnect CN931 and measure the
resistance of the outdoor fan motor.
Is the resistance of outdoor fan motor
normal? (Refer to right table)
Yes
Does the outdoor fan motor rotate smoothly?
Yes
Turn on the power supply to start operation
and measure the voltage of connector CN931.
Is the voltage of connector CN931
normal? (Refer to right table.)
Yes
Turn OFF the power supply and connect
the connector CN931.
Turn ON the power supply and measure
the voltage of connector CN931 while
rotating the motor by the hand.
Does the voltage between pin 7 and pin 4
of connector CN931 repeat 0V and 5V?
Yes
Start operation.
Does the fan motor operate for about
5 seconds?
Yes
Replace the outdoor control P.C. board.
OBH560G
No
Replace the outdoor fan motor.
No
Replace the outdoor fan motor.
CN931 Voltage
pin 1 - pin 4 325 V DC
pin 5 - pin 4 15V DC
pin 6 - pin 4 1 - 5V DC
* To measure the voltage, connect the negative (-)
end of the tester to pin 4.
* Voltage between pin 4 and 6 should be measured
within 1 minute after the operation starts.
No
Replace the outdoor control P.C. board.
No
Replace the outdoor fan motor.
No
Replace the outdoor fan motor.
73
CN931 Outdoor control
P.C. board
Measuring points
pin 1 - pin 4
pin 5 - pin 4
pin 6 - pin 4
pin 7 - pin 4
* To measure the resistance, connect
the negative (-) end of the tester to pin 4.
Resistance
60 kΩ
160 kΩ