How to Safely Replace a Blown AC Dual Run Capacitor
Time required: 20-30 mins · Difficulty 3/5
A run capacitor stores a dangerous electrical charge even after the power is off and can deliver a serious or fatal shock if not discharged properly. Always turn off power at both the outdoor disconnect AND the breaker, then discharge the capacitor with an insulated-handle resistor tool before touching any terminals. If you are not confident handling this safely, call a licensed HVAC technician instead.
Est. DIY Parts: $15 - $25 · Pro Service: $200 - $400 · Est. Savings: $175 - $375
* Estimates based on regional/national contractor rate benchmarks. Actual part prices vary by brand and retailer.
Parts & Tools You'll Need
- Dual Run Capacitor (Match MFD/Voltage Rating Exactly)
- Insulated-Handle Screwdriver Set
- Capacitor Discharge Tool / Resistor
- Multimeter
Step-by-Step Manual
- Cut power at the disconnect AND breaker Pull the outdoor disconnect block near the condenser and also switch off the breaker for the AC at your panel — never rely on just one.
- Discharge the capacitor Using an insulated discharge tool (or an insulated-handle screwdriver as a last resort, touching only the plastic handle), briefly bridge the terminals to release any stored charge.
- Photograph the wiring Take a clear photo of every wire and which terminal (C, HERM/H, FAN) it connects to before disconnecting anything.
- Remove the old capacitor Disconnect each wire terminal, then loosen the mounting strap or bracket and lift the old capacitor out.
- Install and wire the new capacitor Secure the new capacitor (matching MFD and voltage rating exactly) into the mounting bracket, then reconnect each wire to the matching terminal per your reference photo.
- Restore power and test Close the access panel, restore the breaker and disconnect, and run the AC through a full cooling cycle to confirm both the fan and compressor start normally.