An AC capacitor provides an initial burst of electricity so your air conditioner’s motors start successfully. Capacitors store electricity and send it to your system’s motors in compact powerful amounts needed to get your unit revved up as it starts the cooling cycle. When your AC is up and running, the capacitor’s job is to supply a steady current of power until the cycle finishes.

There are multiple capacitors within a given AC unit. These include the “start” capacitors which send signals to start up the motor, and “run” capacitors that regularly send signals to keep the motor running. Typically, there is a capacitor assigned to each compressor, outside fan, and blower motor.

Capacitors fail every day — they do a tough job and, unfortunately, their work takes a toll. There are a few factors that play heavily into the lifespan of your capacitors, though. These include:

Heat Exposure

Voltage Rating


The AC capacitor is one of the most frequently replaced parts of an air conditioner, mainly because it can stop your entire HVAC system from operating if it fails or malfunctions. Should that happen, your air conditioner will have to work harder to circulate cool air in your space, which can eventually wear out your AC unit or result in higher energy bills. 

Keep reading for a breakdown of what you should know about the AC capacitor, including how to spot early signs of trouble and what you can do if yours goes on the fritz.