Description
The Lennox 42J03 is a factory-specified AUTO (automatic reset) limit switch engineered to protect Lennox heating systems from dangerous overheating conditions. Designed as a direct OEM replacement, this limit switch monitors heat exchanger temperatures and automatically interrupts the burner circuit when temperatures exceed the safe threshold, then resets once conditions return to normal — providing continuous, hands-free protection.
Key Features
- Temperature range: 150°F to 190°F (automatic reset)
- AUTO reset operation — restores normal function once temperature drops to safe level
- OEM Lennox replacement part (SKU: 42J03)
- Protects heat exchanger and system components from thermal damage
- Direct drop-in replacement for compatible Lennox furnace models
- Reliable bimetal sensing element for accurate temperature response
Application
The Lennox 42J03 limit switch is designed for use in Lennox gas furnaces and heating systems that require a high-limit safety control within the 150–190°F operating range. It interrupts the burner or blower circuit upon detecting excessive heat, safeguarding the heat exchanger and preventing system damage or unsafe operation.
Why Choose an OEM Limit Switch?
- Ensures compatibility with Lennox equipment specifications
- Maintains system warranty and performance standards
- Engineered for precise trip and reset points matching original equipment design
- Reduces callbacks and repeat service visits
Installation Notes
Always disconnect power before servicing. Verify the replacement limit switch matches the original part number and temperature rating. Consult Lennox equipment documentation for proper mounting location and wiring configuration.
