Carrier 40MPHA Service Manual page 26

DIAGNOSIS AND SOLUTION (CONT)
E3/F5 (Fan speed is operating outside of the Normal Range)
Description: When the indoor fan speed maintains a low speed (ex. 300RPM) or a speed that's too high (ex.1500RPM) for a certain time, the
unit stops and the LED displays the failure (E3). When the outdoor fan speed registers below 200RPM or over 1500RPM for an extended
period of time, the unit stops and the LED displays the failure (F5).
Recommended parts to prepare:
S
Wiring
S
Faulty fan assembly
S
Faulty fan motor
S
Faulty PCB
Troubleshooting and Repair:
Power off , then restart the unit after 2 minutes.
Does a problem remain ?
Shut off the power supply , Rotate
the fan by hand .
Does it turn easily ?
Check the wiring of fan motor
Is it improperly wired ?
Measure the voltage for
the fan motor from the PCB
Is it within normal parameters ?
Replace the fan motor
NO
YES
NO
YES
YES
NO
YES
The unit is operating normally
Find the cause of the problem and resolve it
Ensure proper connections
Replace the indoor /outdoor
PCB
26