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[Lifetime Warranty] 40+5 uF 40/5 MFD 370V or 440 Volt VAC Round Dual Run Capacitor Dual Run Circular Start Capacitor - Compatible for Air Conditioner or Heat Pump Condenser

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40+5 uF (40/5 MFD) 370V/440V Round Dual Run Capacitor

Key Features

  • Dual-Run Functional Design: Combines two capacitors into one compact unit, providing the necessary phase-shift and starting torque for both the compressor (40 uF) and the condenser fan motor (5 uF) in a single high-performance housing.
  • Universal Voltage Rating: Rated for both 370V and 440V AC applications. This 440V-rated capacitor is a superior "universal" replacement that can safely replace older 370V units, offering better heat resistance and longevity.
  • Explosion-Proof Safety Standard: Built with a specialized internal pressure-sensitive interlock (10,000 AFC) that disconnects the capacitor if it overheats or reaches the end of its life, preventing the casing from rupturing.
  • High-Durability Aluminum Casing: Features a rugged, rust-resistant aluminum shell designed to dissipate heat efficiently in the high-temperature environment of an outdoor condenser unit.
  • Maintenance-Free Reliability: Filled with eco-friendly biodegradable oil and rated for 60,000 hours of operation within a wide temperature range (-40°F to +158°F), ensuring year-round climate control stability.

Replaces / Cross-Reference Part Numbers

  • Primary Specifications: 40+5 uF, 40/5 MFD, 40/5 microfarads.
  • Industry Standards: CPT00668, CPT0668, CPT-0668, C4405, USA2234.
  • Brand Equivalents: Mars 12286, Packard PRC405, Titan HD TOC405, GE/Genteq 97F9834.

Compatibility & Fitment

This dual-run capacitor is the standard electrical component for residential and light commercial air conditioning and heat pump systems. Key compatible brands include:

  • Carrier, Bryant, & Payne: Fits hundreds of models in the Comfort, Performance, and Infinity series.
  • Trane & American Standard: Compatible with many XR, XL, and Silver series outdoor condensing units.
  • Lennox: Direct fit for various Merit and Elite series AC units.
  • Rheem & Ruud: Fits standard 2-ton to 3-ton residential condensers utilizing 40/5 capacitance.
  • Goodman & York: Compatible with various GSX, GSC, and Affinity series systems.
  • Note: This is a Round/Circular capacitor. Please verify your mounting bracket can accommodate the round shape if you are replacing an older oval-style unit.

When to Replace

  • AC Won't Start: The most common sign; you hear a clicking sound or the thermostat clicks on, but the outdoor fan and compressor fail to engage.
  • Loud Humming Noise: The outdoor unit emits a loud hum, indicating the motors are receiving power but lack the "kick" from the capacitor to begin spinning.
  • Visible Bulging or Swelling: If the top of the capacitor is domed or "puffed up," the internal safety switch has likely tripped. Replace immediately.
  • Leaking Oil: Visible oily residue on the top terminals or at the base of the capacitor indicates the internal dielectric fluid has escaped.
  • Inconsistent Cooling: The system starts but the compressor "trips" or overheats quickly because the capacitor is no longer providing stable voltage.

Installation Tips

  • Safety First: **CRITICAL:** Turn off the power at the outdoor disconnect box and the indoor breaker. **DANGER:** Capacitors store a high-voltage electrical charge. Use an insulated screwdriver to short across the "C" and "HERM" terminals to discharge the unit before touching it.
  • Label Your Wires: Before removing the old unit, take a photo or label the wires. C = Common (usually Yellow/Black), HERM = Compressor (usually Blue/Red), FAN = Fan Motor (usually Brown).
  • Check the Terminals: Ensure the female spade connectors on your wires are tight. If they are loose or show signs of burning/arcing, replace them to prevent the new capacitor from failing prematurely.
  • Voltage Rule: Remember that a 440V capacitor can replace a 370V unit, but a 370V capacitor cannot be used to replace a 440V unit.
  • Test with Multimeter: If you have a multimeter with a capacitance (MFD) setting, verify the new unit reads within +/- 5% of its 40uF and 5uF ratings before completing the installation.
Product image
  • Step 1

    Step 1

    Turn off the power and locate the capacitor.
  • Step 2

    Step 2

    Discharge any stored electricity by safely shorting the terminals.
  • Step 3

    Step 3

    Take a photo or note the wire connections, then disconnect and install the new capacitor.
  • Step 4

    Step 4

    Reassemble the unit and test to ensure proper operation.

FAQ

This capacitor is used in many residential air conditioner and heat pump condenser units that require a round dual run capacitor rated at 40 + 5 microfarads (uF/MFD). The 40 uF section typically serves the compressor and the 5 uF section typically serves the condenser fan motor. Compatibility depends on matching the electrical ratings and terminal layout required by your equipment, not just the appearance.
Yes, in most HVAC applications a 440 VAC capacitor can replace a 370 VAC capacitor as long as the capacitance rating stays exactly 40/5 uF. The voltage rating can be equal to or higher than the original, but the microfarad rating should match the equipment requirement on the unit data label or original capacitor.
A dual run capacitor combines two capacitors in one can. The 40 uF side is commonly for the compressor, and the 5 uF side is commonly for the condenser fan motor. The terminals are usually labeled C for common, FAN for the fan motor, and HERM for the compressor circuit.
Typical symptoms include the outdoor condenser not starting, a humming compressor or fan, the fan needing a push to start, intermittent cooling, breaker trips during startup, or warm air from the vents while the thermostat is calling for cooling. A swollen top, oil leakage, or a failed capacitance test are also strong indicators.
Check the label on the existing capacitor and match three things: 1) capacitance value: 40/5 uF, 2) voltage rating: 370 or 440 VAC, and 3) style: round dual run capacitor. Also verify your current capacitor uses the standard C, FAN, and HERM terminals and that the replacement will physically fit in the mounting strap or bracket.
Installation is usually straightforward for someone experienced with HVAC electrical service, but the capacitor must be handled carefully because it can store a dangerous charge even when power is off. Typical tools include a screwdriver or nut driver, needle-nose pliers, a phone or labels to mark wire locations, and ideally a multimeter with capacitance testing. Replacement often takes about 15 to 30 minutes.
Turn off disconnect power to the condenser and verify power is absent. Before installing the new capacitor, inspect the contactor, wire terminals, fan motor, and compressor wiring for burned connectors, loose spades, or signs of overheating. If a new capacitor fails quickly, the root cause may be a weak fan motor, hard-starting compressor, high operating temperatures, or poor electrical connections.
Common causes include age, high outdoor heat, voltage stress, frequent cycling, vibration, and internal breakdown over time. Capacitors in condenser units also fail faster when airflow is restricted, the fan motor is dragging, or the compressor is drawing excessive current. Replacing the capacitor without checking overall unit condition can lead to repeat failures.