Lennox 88M91 Hard Start Kit

The Lennox 88M91 Hard Start Kit (Model LB-31200BAR) is an essential OEM compressor start assist designed to provide the necessary mechanical advantage during high-torque startup conditions. As any veteran technician knows, repeated high-amperage draws during the "inrush" phase degrade compressor motor windings and contactor points. This kit utilizes a high-quality start capacitor (rated 176-216 MFD) and a precision potential relay to effectively drop the capacitor out of the circuit once the motor reaches approximately 75% of its synchronous speed. This operation ensures the compressor achieves full rotation almost instantly, which is critical for systems utilizing TXVs (Thermal Expansion Valves) where head pressures may not equalise during the off-cycle. By reducing the duration of locked rotor amps (LRA), this HVAC start assembly minimizes heat buildup and electrical stress within the condensing unit, maintaining system efficiency even in high-ambient environments or low-voltage scenarios common in light commercial and residential applications.

• Enhanced Starting Torque: Provides a significant power boost to overcome high static head pressure, ensuring reliable compressor ignition.
• Reduced Electrical Strain: Decreases the duration of inrush current, protecting internal motor windings and extending the life of the run capacitor.
• Lennox OEM Compatibility: Engineered specifically for Lennox HVAC systems, 13HPX series, and various heat pump models to ensure exact electrical timing.
• Complete Field Kit: Each 88M91 includes the start capacitor, potential relay, and a heavy-duty mounting bracket for quick integration into the electrical cabinet.

When should I install a hard start kit on a Lennox unit?
Installation is recommended if the compressor is "stuttering" during startup, if the lights dim significantly when the AC kicks on, or if the system uses a TXV that maintains high head pressure during the off-cycle.

Is the 88M91 compatible with non-Lennox brands?
While designed as a Lennox OEM replacement, this kit can function in other systems requiring a 176-216 MFD start boost, provided the potential relay's pick-up and drop-out voltages align with the compressor's specs.

Does this kit replace the run capacitor?
No, this is a start-assist component. It works in parallel with your existing run capacitor and is only energized for a fraction of a second during the initial startup phase.

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.