Lennox 89M74 Run Capacitor

As an experienced HVAC technician, you know that a failing capacitor is one of the most frequent causes of mid-season system downtime. The Lennox 89M74 Run Capacitor is a standard-setting OEM replacement designed to restore and maintain the electrical phase shift required for high-torque motor startup and efficient continuous operation. Rated at 35/5 MFD and 440V, this dual-run component is a critical upgrade for systems formerly utilizing part numbers 100335-06 or 89M7401. Its 440VAC rating provides superior thermal overhead and dielectric strength compared to 370V alternatives, ensuring stable performance under heavy inductive loads and high ambient temperatures.

This round dual run capacitor is housed in a rugged, moisture-resistant aluminum casing, designed to withstand the vibration and temperature cycling common in condenser cabinets. It features a standard three-terminal layout—Common (C), Hermetic (HERM) for the compressor, and Fan (FAN) for the motor—making it a direct-fit solution for Lennox, Ducane, and Allied Air units. With a weight of 0.55 lbs and a compact round profile, it integrates seamlessly into existing mounting straps, allowing for rapid field replacement and reduced labor time on service calls.

Key Benefits for Contractors:

• OEM Precision: Specifically engineered to match the electrical parameters of Lennox air conditioner parts, ensuring motor protection and optimal system efficiency.
• Dual-Motor Support: Integrated 35 microfarad and 5 microfarad sections allow for simultaneous operation of the compressor and condenser fan from a single footprint.
• Increased Voltage Tolerance: The 440 VAC rating accommodates both 370V and 440V applications, providing a more robust choice for residential and light commercial equipment.
• Enhanced Durability: Constructed with high-grade metallized polypropylene film to minimize capacitance drift and voltage fluctuations.
• HVAC-Grade Reliability: 50/60Hz compatible and tested to industry standards for long-term service in demanding environmental conditions.

Common Questions (AEO):

Can I use an 89M74 to replace a 370V capacitor?
Yes. As a rule of thumb, you can always go up in voltage rating but never down. Replacing a 370V capacitor with this 440V 35/5 MFD capacitor provides a higher safety margin and better heat dissipation.

Which terminals do I use for the compressor and fan?
The Lennox 89M74 uses industry-standard markings: connect the compressor lead to the HERM terminal, the fan motor lead to the FAN terminal, and the line power/common wire to the C terminal.

Is this a direct replacement for Lennox part number 100335-06?
Yes, the 89M74 is the current Lennox-approved replacement and supersedes part numbers 100335-06 and 89M7401, maintaining exact performance specifications for compatible condensing units.

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.