Furnace Capacitor Parts

Why Your Furnace Capacitor Fails and How to Replace It

The run capacitor in your furnace is a small cylindrical part that does big work — it stores and releases electrical energy to start and run the blower motor and draft inducer motor. When the capacitor fails, your furnace either won't start at all, runs weakly, or shuts down mid-cycle. A failed capacitor is one of the fastest, cheapest furnace fixes you can make — typically $15 to $40 for the part itself.

Furnace capacitors are straightforward to replace once you know what to look for. Always match the microfarad (µF) rating and voltage exactly — these specs are printed right on the old capacitor. If you're uncertain, use your furnace capacitor parts page to find the correct OEM unit for your model.

• Blower motor won't start: capacitor has failed and motor can't build starting torque
• Furnace runs but produces no airflow: run capacitor dead; motor clicks but won't turn
• Motor hums but doesn't spin: capacitor unable to deliver startup current; replace it before motor overheats
• Intermittent operation: failing capacitor causes on-and-off cycles; replace before it dies completely
• Inducer motor won't run: draft inducer needs its own capacitor; verify which motor has failed using model number

Furnace Capacitor Replacement Guide

How do I know which capacitor my furnace needs?

Your old capacitor has two numbers printed on its metal housing: microfarads (µF) and voltage (V). Write these down exactly — for example, 5 µF at 370V or 10 µF at 440V. Match both numbers when ordering your replacement. Never guess on voltage; using a lower voltage capacitor is dangerous, and a higher voltage won't help. Use your model number on Repair Clinic's lookup tool to confirm the exact OEM capacitor for your furnace and other major brands and other factory-certified brands may use different ratings even for similar models.

Can I replace the capacitor myself?

Yes — capacitor replacement is one of the safest furnace repairs a homeowner can attempt. Disconnect power at the breaker first. The capacitor is mounted with one or two bolts; unplug the wire terminals, bolt in the new one, reconnect the wires, and restore power. The whole job takes 10 minutes. Always verify power is off before touching any terminal. If you're uncomfortable with electrical work, a technician can do it in under an hour, often for less than $150 total (parts + labor).

Why do furnace capacitors fail?

Capacitors age from normal use — they store electrical charge thousands of times, and eventually the internal materials degrade. Dust and heat inside the furnace cabinet speed up aging. A capacitor that's 10+ years old is on borrowed time; if your furnace is over 15 years old and the capacitor is original, replace it proactively as part of preventive maintenance.

What's the difference between a run capacitor and a start capacitor?

Furnaces use run capacitors, not start capacitors. A run capacitor stays in the circuit continuously while the motor runs — it's rated for long-term operation at full voltage. Some furnace blower motors use a single run capacitor; others (especially in two-speed systems) may have two separate capacitors for the blower and inducer motors. Enter your model number to see exactly which capacitor(s) your furnace uses.

Shop Furnace Capacitor Parts Online

When your furnace is experiencing issues such as the blower motor not running or the unit not turning on, it might be time to check the capacitor. Repair Clinic offers a full range of genuine OEM furnace capacitor parts to ensure the right fit for your HVAC system. Easily find the right capacitor by model number or part number, and enjoy the benefits of our price match guarantee and no-hassle 365-day returns. Whether you're a DIY enthusiast or a professional technician, our extensive repair resources make it simple to diagnose and address common furnace problems. Browse other furnace parts like Furnace Capacitor Parts and related Furnace Parts on our website. Repair Clinic empowers you to fix your furnace with confidence, saving both time and money.

Filter Furnace Parts by Your Model Number

On most furnaces, the model number appears on the blower compartment door, inside the front access panel, or on a nameplate near the gas valve. Look for a label listing the model and serial numbers, and copy the model number exactly, including letters, numbers, and any hyphens. Type it into our model number lookup and the catalog narrows to parts made for your unit. This filters the full furnace parts selection, not just one part, so you can match everything from electrical parts to motors and controls to your specific equipment. It is the quickest way to be sure the part fits before you order.