An HVAC system Capacitor


A capacitor stores electrical energy to be used when your AC system starts. The “start capacitor” normally supplies a jolt of electricity to help the compressor, fan, or blower start working. Once the AC is up and running, the “run capacitor” then takes over, providing extra power to run it for longer time periods.

AC units will often combine Start and Run capacitors into a single package called a “Dual Round” or “dual run” capacitor. Dual round capacitors are distinguished by having three terminals on the top.


start capacitor, run capacitor, “Dual Round” or “Dual Run” capacitor


CAP, Caps, Cap, C

Related Terms

Amp Clamp

Amp Clamp

An amp clamp is an electronic device that has clamps, used to measure amperage.

Expansion Valve

Expansion Valve

Controls how much refrigerant is allowed to flow into the evaporator coil



Common type of refrigeration used in older home AC systems

Tags - Capacitor

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