Hello. Thanks in advance for any insight / help. My Carrier 3.0 unit is not coming on. Getting a loud hum when it is powered on. Replaced the capacitor and it tried to start. Fan turned very slowly for a couple of revolutions then stopped.
I tried to turn the fan blade by hand to get it going but it was very stiff and would not turn. However, when the power is off, the fan blade spins quite freely. Possibly a bad motor? What else might cause such?
Thanks
Bill
Condenser fan won't start
Check that power is on to the outdoor unit and that the indoor thermostat is calling for cooling and set to cooling mode.
If the compressor/condenser unit has power and the compressor motor appears to be able to start and run normally but the outdoor compressor/condenser fan itself won't turn on, the fan motor may be overheated or damaged
If the motor hums but has trouble starting but can start and run if you give the fan a push with a stick (keep fingers out of fans or risk losing a finger) check/install a blower fan hard start/run capacitor.
A condenser fan that won't start when power is turned on, but whose blades will spin easily when power is off may have a worn fan motor shaft bearing. You may detect this by noticing that you can wobble the fan motor shaft (when power is OFF) or you may notice that you can pull the shaft in and out of the motor (loose end-play).
Condenser fan runs only at unusually slow speed
Possible low voltage at the equipment; possible condenser unit control board circuit failure
Also possibly there may be no power to the fan and fan blades are moving due to local breeze blowing through the unit. On occasion a "slow" outdoor fan may be due to a fan blade that is not secured to the fan motor shaft.
Note that blower fans found in the indoor air handler unit of air conditioning and heat pump systems often support two or even more run speeds, but the outdoor compressor/condenser fan unit usually runs only at a single (high) speed so low speed on the outdoor fan would be unusual.
A slow condenser fan (or air handler unit fan) could be caused by a bad start-run capacitor.
Unfortunately this condition could indicate a burned-out A/C or heat pump compressor motor. If the compressor won't start and if the unit trips a breaker or blows a fuse as soon as it tries to turn on, the motor is burned out and shorted.
If the compressor/condenser unit is wired with 240V (or "220 volts") as most are, an overcurrent at compressor start-up may be tripping just one leg of a two-pole breaker or one of a pair of fuses, leaving the other circuit "live". This can leave the fan motor running.
A bad fan motor can also cause the fan to turn but only abnormally slowly. An internal short that is grounding the fan motor windings can leave the fan running, but abnormally slowly.
Condenser fan noises: ticking, buzzing, humming
Check for a fan blade hitting an obstruction in the unit; possible failing blower fan motor.
Condenser fan motor buzzes or hums
If the fan itself is balanced and undamaged and secured to the shaft and the fan motor buzzes or hums the motor may be damaged, overheated, have an internal bearing failure, or the motor may be hard starting. Check/install a blower fan hard start/run capacitor.
