What MFD capacitor do I need for my Lennox AC?

The correct replacement for Lennox model OEM Lennox Dual Run Capacitor — 21W83 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 Lennox equipment which lists the model number OEM Lennox Dual Run Capacitor — 21W83.

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.

Lennox

OEM Lennox Dual Run Capacitor — 21W83

Name: OEM Lennox Dual Run Capacitor — 21W83
Brand: Lennox
SKU: LNX-21W83
Price: 18.95 USD
Availability: InStock

SKU: LNX-21W83 Brand: Lennox

$18.95 $24.95

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The genuine OEM Lennox 21W83 dual run capacitor combines two capacitors in a single housing to support both the compressor and the condenser fan motor in your Lennox condensing unit. It delivers the continuous phase shift and voltage boost these motors need to start reliably and run efficiently, making it a critical component for steady cooling performance.

A weak or failed dual run capacitor is a leading cause of air conditioning breakdowns. Common symptoms include the compressor or fan humming but not starting, hard starting, tripped breakers, warm air from the vents, clicking sounds at the contactor, and a swollen, leaking, or burst capacitor top. Because it serves two loads, a single failed section can knock out the entire outdoor unit.

Choosing the OEM Lennox 21W83 guarantees the exact dual microfarad and voltage ratings your Lennox equipment specifies. Mismatched aftermarket capacitors can strain the compressor, cause nuisance trips, and shorten component life. This factory-spec replacement installs as a direct drop-in for fast, reliable restoration of full cooling capacity.

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 $75
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

OEM Lennox Dual Run Capacitor — ...

$18.95

Frequently Asked Questions

Does this Capacitor fit my Lennox OEM Lennox Dual Run Capacitor — 21W83?

Yes. This is the factory-specified OEM capacitor for the Lennox OEM Lennox Dual Run Capacitor — 21W83. 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 Lennox OEM Lennox Dual Run Capacitor — 21W83?

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).

Is this capacitor compatible with Bryant or Payne too?

Many Lennox parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.

Should I use OEM or aftermarket for my Lennox 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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OEM Lennox Dual Run Capacitor — 21W83

Shipping Information

Return Policy

Frequently Asked Questions