If your air conditioner is humming but not cooling, clicking when it tries to start, or shutting off after just a few minutes, there's a good chance the problem is a capacitor. The good news: it's one of the cheapest and fastest HVAC repairs out there — usually under $200 and done in under an hour.
What is a capacitor?
A capacitor is a small cylindrical component that gives your AC's motors the electrical boost they need to start and keep running. Your system typically has two: a start capacitor and a run capacitor (or a single dual-run capacitor that handles both). When one fails, the motors can't do their job.
5 signs your capacitor is failing
1. Your AC hums but doesn't start
You hear the system try to kick on — there's a hum — but nothing happens. This is a classic sign the start capacitor isn't giving the motor enough juice to get going.
2. The AC starts, then shuts off after a few minutes
A weak run capacitor can't sustain the motor long enough to complete a full cooling cycle. The system overheats and trips the safety shutoff. This one's easy to mistake for a refrigerant or thermostat issue.
3. You hear a clicking sound when the AC tries to start
That clicking is the system repeatedly trying — and failing — to start the compressor or fan motor. It usually means the capacitor is too weak to complete the startup sequence.
4. The outdoor fan isn't spinning (but the unit is running)
If you look at your outdoor unit and the fan isn't spinning while the compressor is running, that's a strong indicator the fan motor capacitor has failed. Don't let the system run like this — it can burn out the compressor.
5. Your energy bills suddenly jumped
A struggling motor draws more electricity trying to compensate for a weak capacitor. If your bill spiked and your usage hasn't changed, it's worth having the system checked.
What does capacitor replacement cost in Utah?
Most capacitor replacements run $150–$300 in the Salt Lake City and Wasatch Front area, including parts and labor. The part itself is cheap (usually $15–$50); you're mostly paying for the service call and the technician's time. It's a fast repair — typically 30–45 minutes on-site.
Avoid the temptation to DIY this one. Capacitors store a high-voltage charge even after the unit is powered off and can cause serious injury if handled incorrectly.
Can you prevent capacitor failure?
Capacitors wear out over time — most last 10–20 years. A few things accelerate failure:
- Running the system when it's struggling (don't ignore early warning signs)
- Power surges (a surge protector on your AC unit helps)
- Overheating from a dirty condenser coil or restricted airflow
Annual tune-ups catch weak capacitors before they fail completely — which is why it's one of the things we check in every Comfort Club visit.
Think your capacitor might be failing?
We offer same-day HVAC service across the Wasatch Front. Call us or book online and we'll get it diagnosed and fixed fast.