MARS 12745 Run Capacitor

The MARS 12745 Run Capacitor is a high-performance, 40 MFD 440V component specifically designed for continuous duty in HVAC motor and compressor circuits. This round run capacitor features a heavy-duty aluminum case and a non-PCB dielectric, utilizing self-healing metallized polypropylene film for stable operation under high-temperature conditions. Engineered for permanent split capacitor (PSC) configurations, this unit provides the essential phase shift required for compressor startup and efficient blower motor operation in residential and commercial split systems.

Rated for 50/60 Hz and featuring a field-tested temperature range of -40°C to +70°C, the MARS 12745 includes an internal UL-recognized pressure-sensitive interrupter for fail-safe protection. The dual quad-terminals allow for versatile wiring in tight control boxes, while the standard 1-3/4" diameter ensures a precise fit in existing capacitor mounting straps. This commercial-grade HVAC capacitor replacement delivers consistent microfarad output to maintain proper motor torque and reduce internal winding heat.

Key Benefits

• High-grade 40 microfarad capacitance ensures stable motor amperage and power factor correction.
• Dual 440 VAC rating allows for downward compatibility with 370 VAC applications.
• Robust metallized polypropylene film construction prevents premature dielectric breakdown in high-stress cycles.
• UL 810 safety interrupter effectively isolates the capacitor at the end of its service life to prevent rupture.
• Standard round form factor simplifies service work for condenser fan motors and furnace air handlers.

Common Questions

Can I use a 440V capacitor to replace a 370V unit?
Yes, a 440 volt rating is a heavy-duty upgrade over 370 volts. As long as the 40 MFD rating matches, the higher voltage rating provides increased thermal headroom for the motor circuit.

How do I know if this round capacitor will fit my motor strap?
The MARS 12745 features a standard 1-3/4 inch diameter canister. If your original capacitor is a round style with the same diameter, this unit will secure into the existing mounting bracket without modification.

Does it matter which wire goes to which terminal on a run capacitor?
Since this is a single-value 40 MFD capacitor, the terminals are not polarized. However, most technicians utilize one side for the common connection and the other for the start winding leg as per the equipment wiring diagram.

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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.