AC Capacitor Replacement Cost: What to Expect AC capacitor replacement cost is typically $150 to $400 for professional service, including the part and installation. The capacitor itself may cost only $10 to $60 at retail, so DIY can look cheaper. But a capacitor can hold a dangerous electrical charge even after the power is off, and a technician can check whether it is the cause of the cooling problem before replacing it. A failing capacitor may leave your AC humming, struggl