MARS 12739 Run Capacitor

The MARS 12739 Run Capacitor is a high-duty, 40/3 MFD 370V round capacitor engineered for continuous operation in residential air conditioning and heat pump systems. This dual-run component utilizes metallized polypropylene film technology within a hermetically sealed aluminum case to ensure thermal stability and reliable dielectric strength under load. Designed as a universal HVAC replacement part, the 12739 serves both the compressor (40 microfarads) and the condenser fan motor (3 microfarads). The 370Vac rating provides the necessary overhead for 230V circuits, while the non-PCB construction meets modern safety protocols. For contractors, the physical interrupter and pressure-sensitive internal disconnect provide a critical safety layer by preventing case rupture if the capacitor fails. Whether you are performing a seasonal HVAC tune-up or an emergency AC repair, this capacitor offers the consistent capacitance required for optimal motor torque and efficiency. Its round profile and standard terminal configurations allow for rapid mounting in existing brackets, making it a staple for field service technicians.

• Dual Section Design: Simultaneously supports the compressor and fan motor with dedicated 40/3 µF circuits.
• Enhanced Durability: Constructed with high-grade metallized film to withstand internal heat rise and frequent cycling.
• Safe Operation: Includes a built-in internal pressure interrupter to disconnect the circuit in the event of an electrical fault.
• Wide Compatibility: Standardized form factor replaces multiple round dual run capacitor brands and OEM numbers.
• Climate Resilience: Rated for operational temperatures ranging from -40°C to 85°C.

Can I use a 440V capacitor to replace this 370V model?
Yes, a higher voltage rating is acceptable as long as the 40/3 MFD capacitance matches. However, never use a capacitor with a lower voltage rating than the original spec.

Does the physical shape (Round vs. Oval) affect performance?
No, the shape only affects the mounting bracket. If your unit has a round bracket, the 12739 is the correct physical fit; otherwise, an oval capacitor with identical electrical specs would perform the same.

How do I know if my capacitor is failing?
Look for visual signs like a "bulged" or domed top, or use a multimeter to check if the microfarad reading has drifted more than 6% from its rated 40/3 value.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.