Run Start Capacitor, Round, 85/5 MFD, 440/370

Mars 12938 – Dual Motor Run Capacitor for HVAC Applications

The Mars 12938 is a dual-rated motor run capacitor designed to provide continuous electrical support to PSC (permanent split capacitor) motors in HVAC systems. With capacitance ratings of 85/5 microfarads (MFD) and a voltage rating of 440V AC, this round capacitor supports both compressor and fan motor operation from a single device. It is manufactured for long-term use in residential and commercial air conditioning units where high performance and reliable operation are critical.

Constructed with metallized polypropylene film and enclosed in a corrosion-resistant aluminum canister, the Mars 12938 is part of the JARD series and conforms to performance expectations for field replacements, OEM-equivalent service, and scheduled maintenance cycles.

Product Features and Performance Advantages

• ✅ Dual Capacitance – 85 MFD for compressor motor, 5 MFD for fan motor; integrated in a single cylindrical body for space efficiency.
• ✅ Rated for 440V AC – Designed to operate in high-voltage systems and withstand voltage spikes during peak load conditions.
• ✅ Aluminum Round Case – Hermetically sealed to prevent moisture ingress and extend component life.
• ✅ Non-PCB Construction – Built with environmentally safer materials in accordance with current regulations.
• ✅ UL Recognized – Complies with industry-recognized electrical safety and durability standards.

Technical Specifications

• Model: Mars 12938
• Series: JARD
• Capacitance: 85/5 MFD
• Voltage Rating: 440V AC
• Case Type: Round Aluminum
• Application: Dual Motor Run – PSC compressor and fan motors

Installation Guidance

Installation must be carried out by qualified HVAC service professionals. De-energize all equipment and safely discharge capacitors before removal. Confirm capacitance and voltage compatibility with system specifications prior to installation. Verify lead identification and ensure proper torque is applied to secure terminal connections.

• ???? Tools: Nut driver, insulated pliers, mounting bracket hardware
• ???? Test Equipment: Multimeter with MFD and voltage test modes
• ???? Safety: Use PPE including insulated gloves and safety glasses; follow LOTO protocols

Always mount capacitors firmly to prevent vibration damage. If reusing spade terminals, inspect for arcing or fatigue before reconnection.

Recommended Applications

The Mars 12938 is intended for use in air-cooled condensing units, rooftop systems, and heat pumps requiring dual-capacitor support. Its 85/5 MFD profile and high-voltage tolerance make it well-suited for systems with shared motor capacitors operating under continuous load. The unit provides consistent phase shift for both motors, improving energy transfer and reducing motor wear.

Contractor-Specific Benefits

• ✅ Single-Component Efficiency – Supports both compressor and fan motors, reducing parts inventory and installation time.
• ✅ Thermal Stability – Maintains capacitance tolerance across wide ambient temperature ranges.
• ✅ Industry-Compatible Form Factor – Designed for use with standard round capacitor brackets and terminal configurations.
• ✅ Reliable Field Performance – A trusted component for high-cycle installations in demanding service conditions.

Professional Summary

The Mars 12938 is a dual-value capacitor engineered for long-term reliability in HVAC systems utilizing PSC motors. Its 85/5 MFD dual rating and 440V AC capacity allow it to meet the electrical and mechanical demands of modern air conditioning units. Trusted by service professionals for its performance consistency, it serves as a direct replacement in a variety of OEM and aftermarket configurations.