Turn the system off
Set the thermostat to off so the compressor stops trying to start.
AC hums but won’t start, or the outdoor fan won’t spin?
A failed capacitor is one of the most common reasons an air conditioner stops. The outdoor unit hums or clicks but the fan or compressor will not start. Turn the system off and call 833-877-1717. RepairNowUSA connects the request. An independent HVAC technician does the repair.
Am I in the right place?Yes if the outdoor unit hums, buzzes or clicks without running, or the fan does not spin while the compressor tries to start.
Is this urgent?Yes in hot weather. Running a unit that cannot start can overheat the compressor. If anyone shows signs of heat illness, such as confusion, dizziness, nausea, or hot dry skin, call 911 and move them somewhere cool.
What do I do next?Turn the AC off at the thermostat and call 833-877-1717 with the ZIP code and what you hear.
Not sure it is the capacitor? Start at emergency AC repair. Blowing warm air: AC not cooling.
RepairNowUSA editorial review · Last substantively reviewed October 13, 2026 · Review standards
What to do
Check the breaker once
If the AC breaker tripped, reset it once. If it trips again, leave it off.
Do not push the fan
Spinning the fan with a stick is a common tip, and it is dangerous. The unit is live and can start suddenly.
Capacitors hold a dangerous charge
Do not open the outdoor unit, touch the capacitor or wiring, or handle refrigerant. Capacitors hold a dangerous charge even with power off, and refrigerant work requires EPA certification.
Signs of a capacitor or start problem
Humming, no fan
The fan motor has no start boost.
Clicking, then nothing
The compressor tries to start and fails.
Bulging or leaking capacitor
Visible only to the technician inside the panel.
Works sometimes
A weak capacitor can fail on the hottest days.
What to have ready when you call
- Property ZIP code, home or business
- Sounds from the outdoor unit
- Whether the outdoor fan spins
- Whether a breaker tripped
- Indoor temperature and who is inside
- System brand and age, if known
What happens when you call RepairNowUSA
- Describe what is happening in plain words and give the property ZIP code. You do not need to know which trade to ask for.
- RepairNowUSA checks for a participating independent provider who handles AC capacitor and electrical repair in that area.
- If one is available, you are connected. The provider confirms timing, access, scope and price with you before any work.
- The provider, not RepairNowUSA, diagnoses and performs the repair.
RepairNowUSA is a referral and connection service. Provider availability and response times vary by location, time and demand, and are not guaranteed. Before you approve work, ask what was found, the price, the timing and what is not included.
Call 833-877-1717AC capacitor questions
How do I know if my AC capacitor is bad?
The outdoor unit hums or clicks without starting, the fan does not spin, or the system starts only sometimes. A technician confirms it with a meter.
Can I replace an AC capacitor myself?
It is not safe. Capacitors store a high-voltage charge even with the power off.
Can I call at night?
Yes. You can call 833-877-1717 at any time, including nights, weekends and holidays. Whether an independent provider can come out right away depends on your ZIP code, the time and provider capacity, so availability is not guaranteed.
Is a capacitor repair expensive?
It is usually one of the less costly AC repairs. The provider sets the price, so ask for the estimate first.
Do providers work on all AC brands?
Independent HVAC providers commonly work on major brands such as Carrier, Trane, Lennox, Rheem, Goodman, Bryant and York. Tell RepairNowUSA the brand on the call. RepairNowUSA is not affiliated with or authorized by any manufacturer, and warranty work may need the manufacturer’s own network.
Authoritative references
These public sources give general safety context. They do not replace an on-site evaluation, and RepairNowUSA does not perform the work.