Description
Lennox 66J78 AUTO Limit Switch Overview
The Lennox 66J78 is an automatic-reset limit switch engineered to protect furnaces and heating systems from dangerous overheating conditions. Designed as a direct OEM replacement for compatible Lennox equipment, this limit switch provides dependable high-temperature safety control, automatically resetting once temperatures return to a safe operating range.
Key Features
- Auto-reset operation — automatically resets when temperature drops to a safe level, minimizing downtime
- Temperature rating: 310–350°F, providing precise high-limit protection for furnace heat exchangers
- OEM-quality construction for reliable, long-lasting performance
- Direct replacement part for compatible Lennox furnace models
- Helps prevent heat exchanger damage and potential fire hazards caused by overheating
How It Works
The limit switch continuously monitors the temperature within the furnace plenum or heat exchanger area. If the temperature exceeds the rated set point (310–350°F), the switch opens the circuit, shutting down the burner or blower to prevent equipment damage. Once temperatures normalize, the auto-reset function restores normal operation without requiring manual intervention.
Application
- Lennox residential and light commercial furnaces
- High-temperature safety shutoff in forced-air heating systems
- OEM replacement for Lennox part number 66J78
Why Choose the Lennox 66J78?
Using genuine OEM or OEM-equivalent limit switches ensures your furnace operates within safe temperature parameters, protecting both the equipment and occupants. The auto-reset design reduces service calls and keeps heating systems running efficiently. Trust Jackson Systems for fast shipping and expert support on all your HVAC replacement parts.
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