Lennox 87J71 Heat Sequencer Upper Position Electric Furnace Replacement Part

The Lennox 87J71 is a genuine OEM heat sequencer designed for installation in the upper position of compatible Lennox electric furnaces. This critical control component manages the staged activation of heating elements to prevent electrical overload and ensure safe, efficient furnace operation.

How Heat Sequencers Work:

Heat sequencers contain heat-reactive circuits with bimetallic discs that expand and contract in response to temperature changes. When the thermostat calls for heat, the sequencer receives an electrical signal and begins routing power to the first heating element. As each element heats up, the sequencer's internal bimetallic disc bends, closing electrical contacts in a specific sequence to activate subsequent heating elements one at a time. This staged activation prevents all heating elements from turning on simultaneously, which would overload circuits and trip breakers.

Key Functions:

• Staggers heating element activation to distribute electrical load gradually
• Prevents circuit overload and breaker trips during furnace operation
• Controls timing of heating elements and blower motor activation
• Protects heating elements from thermal stress and extends their lifespan
• Ensures optimal heat output without overwhelming the electrical system

Installation Notes:

This sequencer is specifically designed for the upper position in Lennox electric furnace cabinets. Heat sequencers are typically installed between the thermostat and heating elements. Replacement should only be performed by qualified HVAC technicians due to the electrical expertise required for safe installation and proper system operation.

Signs of Sequencer Failure:

Common symptoms of a failing heat sequencer include inadequate heat output (sequencer not activating all elements), no heat production, blower fan running continuously, frequent circuit breaker trips, or electrical odors. Most heat sequencers have an expected lifespan of 12-15 years before replacement becomes necessary.

This is a genuine Lennox replacement part, ensuring proper fit and reliable performance in your electric furnace heating system.