What MFD capacitor do I need for my Lennox AC?

The correct replacement for Lennox model OEM Lennox Dual Run Capacitor — 89M78 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 — 89M78.

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 — 89M78

Name: OEM Lennox Dual Run Capacitor — 89M78
Brand: Lennox
SKU: LNX-89M78
Price: 18.95 USD
Availability: InStock

SKU: LNX-89M78 Brand: Lennox

$18.95 $24.95

OEM Guaranteed

Same-Day Ship

30-Day Returns

Secure Checkout

Texas CMBL #19328542014

SAM.gov Registered

Govt POs Accepted

The genuine OEM Lennox 89M78 dual run capacitor stores and delivers the electrical charge that both your compressor and condenser fan motor need to start and run efficiently. As a dual-rated component, it handles two circuits in a single housing, making it a critical part of your Lennox outdoor unit's operation. It is engineered to match the exact microfarad (MFD) and voltage ratings your Lennox system was designed around.

Common failure symptoms: A weak or failed capacitor is one of the most frequent causes of air conditioner problems. Watch for a compressor or fan that hums but won't start, a fan that spins slowly, intermittent cooling, tripped breakers, or a bulged, leaking, or swollen capacitor top. Capacitors degrade over time from heat and electrical stress, so failures are common in older systems.

Why OEM matters: Using the factory-spec Lennox 89M78 ensures the correct capacitance and voltage tolerances, protecting your compressor and motor from premature wear caused by under- or over-rated aftermarket parts. Genuine Lennox components deliver the reliability and fit your equipment was built for, restoring rated performance and efficiency.

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 — 89M78?

Yes. This is the factory-specified OEM capacitor for the Lennox OEM Lennox Dual Run Capacitor — 89M78. 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 — 89M78?

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.

Menu

OEM Lennox Dual Run Capacitor — 89M78

Shipping Information

Return Policy

Frequently Asked Questions