Siemens Brand 40+10 uF MFD ±5% 370/440 VAC Round Run Start Capacitor - Fits HVAC, Air Conditioners, Heat Pumps
BlueStars 40+10 uF MFD 440 VAC round run capacitor for HVAC and air conditioner units.
BlueStars 40+10 MFD round run capacitor with technical specifications infographic for HVAC systems.
40+10 uF round run capacitor showing 4.72 inch height and 2.36 inch width dimensions for HVAC compatibility.
Air conditioner unit showing symptoms for 40+10 MFD run start capacitor replacement.
40+10 uF round run start capacitor for HVAC systems with label details and terminal view.
Close-up of 40+10 MFD round run capacitor terminals and product label for HVAC and air conditioner systems.
40+10 uF 370/440 VAC round run start capacitor for HVAC systems shown with a technician servicing an AC unit.
Infographic showing wide range applications for 40+10 uF run start capacitor in HVAC, refrigerators, and compressors.
Four-step installation guide for HVAC round run start capacitor showing power shutoff, location, discharge, and wiring.
Infographic showing 45+10 uF round run start capacitor and signs indicating when to replace your HVAC AC capacitor.
BlueStars 45+10 uF 370/440 VAC round run capacitor for HVAC air conditioner systems in a lifestyle marketing graphic.
BlueStars 40+10 uF MFD 440 VAC round run capacitor for HVAC and air conditioner units.
BlueStars 40+10 MFD round run capacitor with technical specifications infographic for HVAC systems.
40+10 uF round run capacitor showing 4.72 inch height and 2.36 inch width dimensions for HVAC compatibility.
Air conditioner unit showing symptoms for 40+10 MFD run start capacitor replacement.
40+10 uF round run start capacitor for HVAC systems with label details and terminal view.
Close-up of 40+10 MFD round run capacitor terminals and product label for HVAC and air conditioner systems.
40+10 uF 370/440 VAC round run start capacitor for HVAC systems shown with a technician servicing an AC unit.
Infographic showing wide range applications for 40+10 uF run start capacitor in HVAC, refrigerators, and compressors.
Four-step installation guide for HVAC round run start capacitor showing power shutoff, location, discharge, and wiring.
Infographic showing 45+10 uF round run start capacitor and signs indicating when to replace your HVAC AC capacitor.
BlueStars 45+10 uF 370/440 VAC round run capacitor for HVAC air conditioner systems in a lifestyle marketing graphic.
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40+10 uF MFD ±5% 370/440 VAC Round Run Start Capacitor - Fits HVAC, Air Conditioners, Heat Pumps

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40+10 uf 40+10 MFD 370-440VAC ±5% Volts Round Run Start Capacitor

Key Features

  • Dual capacitance rating: 40 microfarad (uF) for compressor, 10 uF for fan motor
  • Dual voltage rating: 370 or 440 VAC
  • Capacitance tolerance: ±5%
  • Operating frequency: 50/60 Hz
  • Case: Round aluminum can with moisture and oil resistance
  • Terminals: Three-post design (C, FAN, HERM) with 1/4 inch male quick-connects
  • Operating temperature: -40°C to 70°C (-40°F to 158°F)
  • Safety protection: 10,000 AFC (Ampere Fault Current) internal protector

Replaces / Cross-Reference Part Numbers

  • Replaces any dual round motor run capacitor with matching 40/10 uF and 370V or 440V specifications.
  • Check the label of your original capacitor for matching capacitance (e.g., 40/10, 40+10, 40+10 MFD) and voltage ratings.
  • Known to replace parts such as USA2232A and 40/10DVR.

Compatibility & Fitment

  • Designed for continuous duty in single-phase motor applications.
  • Common in residential and light commercial HVAC systems.
  • Suitable for use in:
    • Air conditioner condensing units
    • Heat pumps
    • Compressor motors
    • Condenser fan motors
    • Refrigeration systems

When to Replace

  • Compressor or fan motor fails to start or struggles to start.
  • A humming sound is audible, but the motor does not engage.
  • Capacitor casing is visibly swollen, bulging, cracked, or leaking fluid.
  • The unit starts but shuts down after a short period.
  • A capacitance test reading is outside the specified ±5% tolerance.

Installation Tips

  • Disconnect all electrical power to the main unit before beginning work.
  • Safely discharge the existing capacitor by shorting across the terminals with an insulated screwdriver (e.g., C to HERM, then C to FAN).
  • Verify the uF (MFD) and voltage ratings of the replacement capacitor match the component being replaced. The voltage rating can be equal to or higher, but never lower.
  • Document or photograph the wire connections to each terminal (C, FAN, HERM) before disconnecting.
  • Ensure the new capacitor is physically secured with the original mounting bracket.
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  • Step 1

    Step 1

    Turn off the power and locate the capacitor
  • Step 2

    Step 2

    Discharge any stored electricity by shorting the terminals
  • Step 3

    Step 3

    Take a photo or note how the wires connect. Disconnect wires & install the new capacitor.
  • Step 4

    Step 4

    Reassemble and test

FAQ

This dual-run capacitor is designed for use in HVAC systems, including residential and commercial air conditioners, heat pumps, and refrigeration units. It provides power to both the compressor motor and the condenser fan motor from a single unit.
This unit replaces a wide range of 40/10 MFD capacitors, including common industry references such as C34010, C34010R, C44010, C44010R, USA2232A, 14088, 12798, 12746, 12246, 12088, and 97F9831.
Common symptoms of a failing capacitor include the air conditioning unit failing to start, a humming sound from the compressor without the fan turning, or the fan motor struggling to reach full speed. If the top of the capacitor appears domed or swollen, it has likely failed and requires immediate replacement.
Yes. This capacitor is dual-rated for both 370 VAC and 440 VAC. Using a 440V-rated capacitor in a 370V application is perfectly acceptable and often provides a higher safety margin for the component.
Installation typically takes 15 to 30 minutes. You will need a screwdriver to remove the HVAC service panel and a pair of needle-nose pliers to disconnect and reconnect the spade terminals. Always ensure the power to the unit is completely shut off at the disconnect box or breaker before beginning.
Before handling the old capacitor, you must discharge it by placing an insulated screwdriver across the terminals to prevent electrical shock. Additionally, verify that the microfarad (MFD) rating and voltage match your system requirements, and ensure the wire connections are clean and tight when installing the new part.