When the fan on top of your outdoor unit will not spin but the unit is humming, the most common cause is a failed run capacitor, the part that gives the fan motor its starting push. The next most likely causes are a burned-out fan motor, a contactor that is not passing power, or something physically jamming the blade, a stick, ice, or debris. A quick and telling test some techs use: with the system on, if the fan starts spinning after you nudge the blade with a stick through the grille, the capacitor is almost certainly weak. Important: do not keep running the AC with the fan stopped. Without that airflow the compressor overheats fast and can be ruined, turning a cheap capacitor fix into a very expensive one. Shut the system off at the thermostat and the breaker, and get it diagnosed. Call LA Heating & Air at (818) 660-1062 for same-day service.
