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340-408 MFD 110-125V Start Capacitor — Universal Motor Starting
National HVAC Parts

340-408 MFD 110-125V Start Capacitor — Universal Motor Starting

SKU: NHVAC-CAP-3GO76D Brand: National HVAC Parts
$9.99 $13.99

Order before 3PM CST — ships same day.
Standard delivery 2-5 business days. Express options at checkout.

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340-408 MFD start capacitor for HVAC compressors and PSC motors. The start capacitor provides the extra torque burst needed during motor startup, then disconnects from the circuit once the motor reaches running speed (via a potential relay or PTCR device).

Specifications

  • Capacitance: 340-408 MFD
  • Voltage: 110-125 VAC
  • Type: Electrolytic motor start
  • Shape: Round black cylinder
  • Duty: Intermittent (start only — not for continuous run)

Frequently Asked Questions

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

A start capacitor provides high starting torque for a brief moment during motor startup. A run capacitor stays in the circuit continuously. They are NOT interchangeable — a start cap left in the circuit will overheat and explode. Start caps are typically black cylinders with much higher MFD values than run caps.

Why does the MFD have a range instead of a fixed value?

Start capacitors use electrolytic construction with wider tolerances than run capacitors. The 340-408 MFD range means the actual capacitance falls somewhere in that range. As long as the range overlaps with your original cap's range, it will work correctly.

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 $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

Frequently Asked Questions

Does this Capacitor fit my National HVAC Parts 340-408 MFD 110-125V Start Capacitor — Universal Motor Starting?
Yes. This is the factory-specified OEM capacitor for the National HVAC Parts 340-408 MFD 110-125V Start Capacitor — Universal Motor Starting. 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 340-408 MFD 110-125V Start Capacitor — Universal Motor Starting?
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 National HVAC Parts 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 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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