AC Capacitor Replacement Cost
A failed run or start capacitor is one of the most common AC repairs. The outdoor unit hums, the fan will not spin, or the AC starts and stops. The part costs $10 to $50, and a technician typically charges $120 to $400 installed. Capacitors store high voltage even with the power off, so this is a job for a pro.
Typical pro cost
$120 to $400
- Urgency
- Fix soon
- DIY difficulty
- Hard
- Time to fix
- About 30 minutes (pro)
- Prices
- US typical range
Last reviewed September 2026
Signs it's this problem
- Outdoor unit hums but the fan does not spin
- AC takes a long time to start or clicks on and off
- Warm air from the vents
- The top of the capacitor is bulging or leaking
- AC shuts off by itself
Common causes
Heat and age
Capacitors weaken over time, especially in hot climates.
Power surges
Lightning and grid surges can destroy them.
Wrong size replacement
An incorrect rating fails early or strains the motors.
Overworked system
A dirty coil or low refrigerant makes motors draw more power.
How to fix it, step by step
- 1
Turn the thermostat off and switch off the outdoor disconnect and the breaker.
- 2
Look at the outdoor fan. If it does not spin but the unit hums, the capacitor is a likely cause.
- 3
Do not open the panel or touch the capacitor yourself. It can hold a dangerous charge.
- 4
Call an HVAC technician to test it with a meter and replace it with the exact microfarad (MFD) and voltage rating.
- 5
Ask whether a hard-start kit makes sense for an older compressor.
- 6
After the repair, change the filter and keep the outdoor coil clean to reduce strain.
Tools and materials
- None for homeowners: this is a pro repair
Approximate DIY cost: Not a DIY job
Call a pro when
- Any capacitor replacement
- The unit hums or clicks without starting
- The breaker trips when the AC starts
AC Capacitor Replacement Cost cost
| Job | Typical cost |
|---|---|
| Run or start capacitor, installed | $120–$400 |
| Dual run capacitor, installed | $150–$450 |
| Hard-start kit, installed | $150–$400 |
| AC service call | $75–$200 |
Ranges are typical US prices compiled by FixHomeCost. Prices vary by region, home and contractor, so compare 2–3 local quotes.
Common questions
How do I know if my AC capacitor is bad?
Common signs are a humming outdoor unit with a fan that will not spin, slow or failed starts, warm air, and a swollen capacitor top. A technician confirms it with a meter.
How long does an AC capacitor last?
Often about 10 to 20 years, but heat and power surges can shorten that considerably.
Can I run my AC with a bad capacitor?
No. The motors can overheat and fail, turning a small repair into a compressor or fan motor replacement.
Why is capacitor replacement so expensive when the part is cheap?
Most of the cost is the service call, diagnosis and labor. Prices also vary by region and by whether it is an after-hours visit.
Related guides
This is general information, not a professional inspection. See how we research costs.