Different AC units require different capacitors to run. Generally, the larger your AC unit, the more you'll likely pay for an AC capacitor. Additionally, it's often more difficult to find appropriate parts for outdated AC units, so if yours is old, make sure to budget a little extra for parts. It's not always easy or obvious for a pro to diagnose a faulty capacitor. In many cases, they'll need to run several tests to determine whether the capacitor is the problem or if something. HVAC technicians can be in short supply, especially when demand is particularly high. And when demand is high, costs often go up. So if your AC unit goes out during the height of. Your region can affect labor costs. In general, if you live in an area with a high cost of living, you'll usually need to pay a pro more than you would if you lived in an area with a lower cost of. The time of day when your AC unit goes out can also affect your costs. If it breaks outside of normal business hours and you need someone to come in.