Quick answer
A part that stores and delivers the jolt to start motors.
A capacitor stores electrical energy and provides the surge needed to start and run the compressor and fan motors. Capacitors are common, inexpensive failure points — especially after hot summers — and a failed capacitor often presents as a system that hums but won't start.
Why Capacitor matters
Component terms point to the specific part affecting comfort, safety, or reliability. Knowing the component helps you understand whether a repair is minor, urgent, or a sign of larger system wear.
When you'll see this term
You will usually hear this term during troubleshooting, repair estimates, tune-ups, and warranty conversations.
Questions to ask your technician
- What caused this component to fail?
- Is replacing it a lasting fix, or a temporary repair on an aging system?
- Are there safety or warranty concerns tied to this part?
Go deeper
How often should you service your HVAC system?