Run Capacitor, Round, 50/12.5 MFD, 440/370

Mars 12253 – 50/12.5 MFD 440V Dual Run Capacitor, Round Aluminum Case

The Mars 12253 is a dual-section motor run capacitor rated at 50/12.5 microfarads (MFD) and 440 volts AC. Designed for use in permanent split capacitor (PSC) systems, this round capacitor supports both compressor and condenser fan motor operation within a single-phase HVAC circuit. Manufactured to meet EIA-456-A performance standards, it provides reliable operation in continuous-duty conditions across residential and light commercial applications.

As part of the Mars Blue Box series, this model features a rolled aluminum shell, oil-filled non-PCB dielectric, and a pressure-sensitive interrupter to ensure safe shutdown in fault conditions.

Technical Specifications

• Capacitance: 50/12.5 MFD ±6%
• Voltage Rating: 440 VAC, 50/60 Hz
• Configuration: Dual-section run capacitor for compressor and fan motor
• Case Type: Round aluminum
• Dielectric Fluid: Oil-filled, non-PCB
• Operating Temperature: -40°C to +70°C
• Terminals: ¼-inch male quick-connect (C, HERM, FAN)

Physical Dimensions

• Diameter: Approx. 2.5 inches
• Height: Approx. 4.8 inches (excluding terminals)

Installation Guidelines

Installation of the Mars 12253 should be performed by qualified HVAC personnel. Before replacement, verify that the capacitor ratings match system requirements. Ensure the system is powered down and the existing capacitor is fully discharged prior to removal. Use appropriate terminal connections and mounting hardware to prevent vibration-related failure. All wiring must follow OEM diagrams and comply with local electrical codes.

Intended Application

This dual capacitor is commonly installed in split-system air conditioners and heat pumps, supporting both the compressor (50 MFD) and the condenser fan motor (12.5 MFD). It simplifies system layout by combining two capacitance values into one component, reducing space requirements and inventory complexity.

Key Features for Field Use

• ✅ Dual-Capacitance Design: Supports both compressor and fan motor in PSC systems
• ✅ 440V Voltage Rating: Designed for high-stress environments and surge-prone circuits
• ✅ UL Recognized: Complies with national safety standards for HVAC components
• ✅ Pressure-Sensitive Interrupter: Safely disables capacitor during fault conditions
• ✅ Field-Ready Form Factor: Round case fits standard brackets in OEM and retrofit configurations