Forced-Air HVAC (heating and cooling — PSC or ECM blower)
Blower Not Running Troubleshooting
Step-by-step diagnostic for indoor blower motors that won't start, run intermittently, or fail to maintain operation during heating or cooling calls.
Safety Notice
Disconnect all power before accessing blower compartments. Blower motors involve line voltage, rotating parts, and capacitors that store charge. Only trained, qualified technicians should perform these procedures. Follow NFPA 70E and local codes.
Blower Not Running — Overview
This workflow helps diagnose why the indoor blower (air handler fan) is not running when expected. Common causes include thermostat settings, safety switches, loss of power, control board relay failures, bad capacitors, and motor faults. Before starting: • Confirm the system has power at the main disconnect / breaker. • Note the thermostat mode and fan setting. • Note whether the complaint occurs during heating, cooling, or fan-only operation.
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