Carrier 38MGRBQ18B-3 - DIAGNOSIS AND SOLUTION (CONT); Outdoor Fan Speed Malfunction

38MGRBQ: Service Manual
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DIAGNOSIS AND SOLUTION (CONT)
E8/ EC 07 (Outdoor fan speed malfunction)/ EC 71(Over current failure of outdoor DC fan motor) diagnosis and
solution
Troubleshooting
ERROR CODE
E8/ EC 07/ EC 71
MALFUNCTION DECISION
CONDITIONS
When outdoor fan speed remains too low (300RPM) or too high (2400RPM) for a certain time, the unit will stop
and the LED displays the failure.
SUPPOSED CAUSES
Wiring mistake
Faulty fan assembly
Faulty fan motor
Faulty PCB
,
s
.
?
Power off, then restart the
unit 3 minutes later. Is it still
displaying the error code?
,
.
The unit operates normally.
.
,
or
.
.
?
Check the wiring of fan
motor. Are all the
connections good?
No
Yes
No
.
Correct the connections
.
No
Replace the fan motor
Yes
Yes
Replace the main PCBNo
1
?
Check whether the main PCB
is normal through index 1?
Yes
No
Find the cause and fix it.
For example, whether
the fan is blocked or
the screws which secure
the fan are tight.
Shut off the power supply,
rotate the fan by hand.
Does it rotate properly?