What MFD capacitor do I need for my National HVAC Parts AC?

The correct replacement for National HVAC Parts model 45+10 MFD 370/440V Dual Run Capacitor is this exact part. It is the factory-specified replacement with exact OEM specifications. Using a part with different specifications can cause equipment damage or void your warranty. You can verify this by checking the data plate on your National HVAC Parts equipment which lists the model number 45+10 MFD 370/440V Dual Run Capacitor.

My AC hums but will not start. What part do I need?

An AC that hums but will not start is the classic symptom of a failed capacitor. The capacitor provides the electrical boost needed to start the compressor and fan motors. When it fails, you hear the hum of the motor trying to start but it cannot overcome inertia. Other symptoms include the fan spinning slowly, the AC cycling on and off rapidly, or a visibly swollen or leaking capacitor. Replacement cost: $15 to $80 for the part, DIY in 30 minutes.

National HVAC Parts

45+10 MFD 370/440V Dual Run Capacitor

Name: 45+10 MFD 370/440V Dual Run Capacitor
Brand: National HVAC Parts
SKU: NHVAC-CAP-K4BNRI
Price: 20.95 USD
Availability: InStock

SKU: NHVAC-CAP-K4BNRI Brand: National HVAC Parts

$20.95

Market price $24.64

SAVE $3.69 (15%) vs market

Genuine National HVAC Parts OEM part · Guaranteed to fit your unit

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Texas CMBL #19328542014

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45+10 MFD dual run capacitor for AC systems with larger fan motors requiring 10 MFD. The 45 MFD side powers the compressor, the 10 MFD side powers the condenser fan motor.

Specifications

Capacitance: 45+10 MFD (±6%)
Voltage: 370/440 VAC
Terminals: 3-prong — HERM, FAN, COM

Why would my system need a +10 instead of +5?

Larger condenser fan motors (typically 1/3 HP and above) require a 10 MFD run capacitor instead of 5 MFD. Always match the MFD value listed on your existing capacitor or on the motor nameplate.

Fitment Guaranteed — if this capacitor doesn't work in your system, we'll send the right one or refund you.

Ships same-day from Houston, TX on orders before 3PM CST.

Shipping Information

Orders placed before 3PM CST ship same business day
Standard delivery: 2-5 business days
Express shipping available at checkout
Free shipping on orders over $99
Tracking number emailed upon shipment

Return Policy

30-day returns on unused parts in original packaging
Electrical parts (capacitors, contactors, control boards) are final sale once installed
Email info@nationalhvacparts.com to initiate a return
Refunds processed within 5-7 business days

45+10 MFD 370/440V Dual Run Capa...

$20.95

Frequently Asked Questions

Does this Capacitor fit my National HVAC Parts 45+10 MFD 370/440V Dual Run Capacitor?

Yes. This is the factory-specified OEM capacitor for the National HVAC Parts 45+10 MFD 370/440V Dual Run Capacitor. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.

How do I replace the capacitor on my National HVAC Parts 45+10 MFD 370/440V Dual Run Capacitor?

Difficulty: Easy (20–30 min)
Step 1: Turn off power at breaker. Step 2: Open condensing unit panel. Step 3: Photograph the old capacitor wiring (Common/Herm/Fan). Step 4: Discharge old capacitor with insulated screwdriver. Step 5: Disconnect and remove old capacitor. Step 6: Mount new capacitor, reconnect wires to matching terminals. Step 7: Close panel, restore power, test. Tools: screwdriver, needle-nose pliers.

My AC hums but won’t start. What part do I need?

An AC that hums but won’t start is the classic symptom of a failed capacitor. The capacitor provides the electrical boost to start the compressor. When it fails, you hear humming but the motor can’t overcome inertia. Other symptoms: fan spinning slowly, AC cycling on/off rapidly, or a visibly swollen capacitor. Fix: replace capacitor ($15–$80 DIY, 30 min).

Will this capacitor fit brands other than National HVAC Parts? +

Cross-brand compatibility varies by part. The safest method is matching the exact OEM part number stamped on your old part. If you are unsure, email info@nationalhvacparts.com with your equipment model number and we will verify the correct replacement before you order.

Should I use OEM or aftermarket for my National HVAC Parts capacitor?

OEM strongly recommended. OEM capacitors have ±6% MFD tolerance vs aftermarket ±10%. The looser tolerance causes motor winding stress, higher temps, and shorter compressor life. Price difference is only $10–$20 — OEM is the clear value choice.

How fast does National HVAC Parts ship?

Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.

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