How to Replace an AC Capacitor

A failed run capacitor is one of the most common reasons a residential AC unit stops cooling. The good news: it's usually a quick, inexpensive fix if you're comfortable working around electrical components.

Tools you'll need

• Insulated screwdriver
• Nut driver or socket set
• Needle-nose pliers
• Multimeter (recommended)
• Replacement capacitor matching your unit's specs

Step 1 — Confirm the capacitor is the problem

Symptoms of a failed capacitor include: humming compressor that won't start, fan that won't spin (but spins if you push it with a stick), or a unit that trips the breaker. A bulging or leaking capacitor top is a dead giveaway.

Step 2 — Cut power

Turn off the breaker AND pull the outdoor disconnect. Verify with a multimeter before opening the access panel.

Step 3 — Discharge and inspect

Use an insulated screwdriver across the capacitor terminals to safely discharge stored voltage. Take a clear photo of the wiring before you disconnect anything.

Step 4 — Match the replacement

Capacitors are rated by microfarads (µF) and voltage. Your replacement MUST match both. Common AC capacitors are dual-run (e.g., 45/5 µF, 370V or 440V). Check the side of the old cap and order the same spec.

Step 5 — Install and power up

Connect the new capacitor matching your photo: HERM, FAN, and C (common) terminals. Secure the strap, close the panel, restore power, and watch the unit start cleanly.

If you're in South Florida, we stock OEM capacitors for same-day pickup or local delivery. Need help matching a part? Text us a picture of your unit label.