A system that hums but moves no air, a blower that only starts after a tap, weak airflow at every register, or a breaker tripping on startup all point at the blower assembly or its capacitor. Capacitors are inexpensive parts that fail gradually, and a weak one makes the motor draw high current and run hot until it burns out. ECM motors on newer equipment fail differently, usually at the control module rather than the motor itself.
This is not a do-it-yourself check. Capacitors hold a charge long after the power is off. Running a system with a stalled blower also risks overheating the heat exchanger, which is a safety issue rather than an inconvenience. Pro HVAC connects homeowners in Shaker Heights, OH with HVAC professionals. Call (321) 463-9811.