Mitsubishi Electric MXZ-3C24NA Service Manual page 72

• Fan motor does not operate or stops operating shortly after starting the operation.
Check of outdoor fan motor
Disconnect CNF1 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 CNF1.
Is the voltage of connector CNF1
normal? (Refer to right table.)
Yes
Turn OFF the power supply and connect
the connector CNF1.
Turn ON the power supply and measure
the voltage of connector CNF1 while
rotating the motor by the hand.
Does the voltage between pin 7 and pin 4
of connector CNF1 repeat 0V and 5V?
Yes
Start operation.
Does the fan motor operate for about
5 seconds?
Yes
Replace the outdoor control P.C. board.
OBH702A
No
Replace the outdoor fan motor.
No
Replace the outdoor fan motor.
CNF1 Voltage
pin 1 - pin 4 294/325 VDC
pin 5 - pin 4 15 VDC
pin 6 - pin 4 1 - 5 VDC
* 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.
72
CNF1
Outdoor control
P.C. board
Measuring points Resistance
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.