Carrier 38MBRC Series - LACK PHASE FAILURE DIAGNOSIS; EC 72 Troubleshooting

38MBRC: Service Manual
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EC 72 (Lack Phase Failure of Outdoor DC Fan Motor Diagnosis and Solution)
Description: When the three-phase sampling current of the DC motor is abnormal, especially when the current of one or more phases is
always small and almost 0, the LED displays the failure code.
Recommended parts to prepare:
• Connection wire
•Fan motor
• Outdoor PCB
Troubleshooting and repair:
Check the fan three -phase
output for obvious open circuit
Power o ,then restart the unit
2 minutes later. Is it still
displaying the error code ?
The unit operates
normally
Check the wiring of fan
motor.Are all the connections
good?
Correct the connections
Check whether the three -
phase resistance of the fan is
symmetrical
Replace the fan motor
Yes
Yes
Yes
No
No
No
Replace the main PCB
No
Problem solved
Yes