AC compressor not starting — Fresno, California

When the outdoor AC unit hums, clicks, or stays completely silent while the indoor fan blows warm air, the compressor likely isn't starting. Common causes include a failed capacitor, a burned-out compressor motor, a tripped high-pressure switch, or low refrigerant levels. The compressor is the most expensive component in the system — running a failing one can cause total unit failure. An HVAC technician can diagnose whether the fix is a $150 capacitor swap or a compressor replacement that may justify upgrading the entire system.