A number of online stores, including RepairClinic and Grainger, carry air conditioning capacitors for various brands. Local home improvement stores, such as The Home Depot and Lowe's, might stock replacement parts for models they sell.
Before looking for a replacement capacitor, identify the kind of capacitor the system needs. Almost all air conditioners have a run capacitor, which is used to power the motors that remove heat from the system. Run capacitors are also used to power the fans that send electricity through the structure. Many models also have start capacitors that help kickstart the system and speed up the energy-intensive starting process. Using the wrong capacitor can damage expensive components within the system.