Lennox 86K78 Relay Kit

The Lennox 86K78 Relay Kit is a critical 24v 3PDT relay kit engineered for precise switching in professional HVACR systems. As a triple pole double throw relay, this component is designed to manage complex electrical sequences, commonly serving as a defrost relay kit in heat pump configurations. Technicians often source this part when diagnosing issues with compressor control signals or outdoor coil frost management. This genuine OEM assembly ensures exact fit and low-resistance contact performance, which is vital for maintaining system efficiency during high-demand heating cycles. The 86K78 is the direct replacement for 86K7801 and 81F05, providing a streamlined solution for retrofitting older Lennox units without requiring field modifications to the mounting bracket or wiring harness. Utilizing a 24-volt AC coil, it integrates seamlessly with standard 24V control circuits to isolate high-power loads from sensitive electronic control boards. For contractors performing preventative maintenance or emergency repairs, keeping this Lennox replacement part on the truck ensures reliable restoration of the defrost logic and motor switching functions.

• OEM Compatibility: Specifically designed to replace legacy 86K7801 and 81F05 relays with zero field modification.
• 3PDT Configuration: Provides three poles for versatile switching, allowing a single 24V signal to control multiple independent high-voltage circuits.
• Defrost Logic Support: Essential for managing the transition between heating and defrost modes to prevent coil icing in heat pump systems.
• Industrial Build Quality: Constructed with heavy-duty contacts to withstand high-frequency switching and vibration common in outdoor condenser units.

What are the signs that a defrost relay kit needs replacement?
If the outdoor coil is completely iced over or the system fails to enter defrost mode despite the control board triggering the signal, the relay contacts may be pitted or the 24V coil may have failed. Always check for 24V at the coil before replacing.

Is the 86K78 compatible with non-Lennox equipment?
While the 86K78 is a standard 3PDT 24V relay, it is specifically configured with Lennox-specific mounting and terminal spacing. It is best used as a direct replacement for Lennox part numbers 86K7801 and 81F05 to ensure proper fitment.

Can I use this relay for motor starting applications?
Yes, the 3PDT configuration is suitable for switching small motors and fans within its rated amperage. Ensure the full load amps (FLA) of the motor do not exceed the contact ratings of the relay.

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.