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.