What MFD capacitor do I need for my Lennox AC?

The correct replacement for Lennox model OEM Lennox Single Run Capacitor — Y4603 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 Single Run Capacitor — Y4603.

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.

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Lennox

OEM Lennox Single Run Capacitor — Y4603

Name: OEM Lennox Single Run Capacitor — Y4603
Brand: Lennox
SKU: LNX-Y4603
Price: 18.95 USD
Availability: InStock

SKU: LNX-Y4603 Brand: Lennox

$18.95 $24.95

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The genuine OEM Lennox Y4603 single run capacitor stores and delivers the electrical charge that keeps your compressor or fan motor running smoothly and efficiently. Installed in Lennox condensing units and air handlers, this component provides the continuous phase shift a single-phase motor needs to maintain proper torque and draw the correct amperage under load.

When a run capacitor weakens or fails, you may notice the motor humming but not starting, intermittent shutdowns on thermal overload, warm air instead of cool, or a compressor that trips the breaker. A bulging or leaking capacitor top is a clear sign it needs immediate replacement to prevent damage to the motor windings.

Using the OEM Lennox Y4603 guarantees the exact microfarad (µF) rating and voltage tolerance your Lennox equipment was engineered for. Generic substitutes with mismatched ratings can shorten motor life, reduce efficiency, and void manufacturer coverage. Choose the factory part for a precise fit and rated performance.

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 Single Run Capacitor ...

$18.95

Frequently Asked Questions

Does this Capacitor fit my Lennox OEM Lennox Single Run Capacitor — Y4603?

Yes. This is the factory-specified OEM capacitor for the Lennox OEM Lennox Single Run Capacitor — Y4603. 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 Single Run Capacitor — Y4603?

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 Single Run Capacitor — Y4603

Shipping Information

Return Policy

Frequently Asked Questions