MARS 12798 Run Capacitor

The MARS 12798 Run Capacitor is a high-performance 40/10 MFD 440V dual run capacitor designed for demanding HVACR applications. Engineered for standard round dual run capacitor replacements, this component supports both the compressor (40 microfarads) and the fan motor (10 microfarads) in residential and light commercial condensing units. With a 440VAC rating, it is backwards compatible with 370V systems, providing a robust overhead for voltage fluctuations and reducing truck stock requirements for field technicians. The physical build features a non-PCB, oil-filled aluminum case with a patented pressure-sensitive interrupter (PSI) for safety. Operating within a temperature range of -40°C to 70°C, this 40+10 microfarad 440Vac unit ensures stable capacitance under high-thermal loads. Utilizing standard 1/4-inch quick-connect terminals, the MARS 12798 enables seamless integration into existing wiring harnesses, maintaining system efficiency and protecting motor windings from premature failure due to phase-angle instability.

Key Benefits:

• Enhanced Compatibility: Dual-rated for 370V and 440V applications, making it a versatile 40/10 capacitor for various OEM equipment.
• Industrial Safety Standards: Features a pressure-sensitive interrupter and is UL/CSA recognized to ensure secure operation during internal fault conditions.
• Optimized Motor Performance: Provides the precise phase shift required for high-torque startups and continuous run-cycle efficiency.
• Durable Construction: Housed in a corrosion-resistant aluminum shell designed to withstand rigorous outdoor environments.
• Standardized Form Factor: The round cylindrical design fits most standard motor capacitor brackets and mounting straps.

Common Questions:

Can I use a 440V capacitor to replace a 370V capacitor?
Yes. In HVAC motors, you can always go up in voltage, but never down. Using a 440V rated capacitor like the 12798 to replace a 370V part provides a higher safety margin without affecting performance.

Does the MARS 12798 have a polarity for the terminals?
No, AC run capacitors are non-polarized. However, on a dual capacitor, you must ensure the 'HERM', 'FAN', and 'C' (Common) terminals are correctly mapped to your compressor and fan wires respectively.

What causes a 40/10 MFD capacitor to swell or fail?
Failure is typically caused by high ambient temperatures, voltage spikes, or motor age which increases the current draw. The internal interrupter in this MARS unit is designed to disconnect the capacitor if internal pressure builds, preventing case rupture.

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.