Lennox 18J37 Auto Limit Switch F - 175 F-205

The Lennox 18J37 is an automatic limit switch designed for HVAC furnace applications. This safety control features a 175°F cut-in temperature and 205°F cut-out temperature, providing essential overheat protection for residential and light commercial heating systems.

Key Features:

• Automatic reset limit switch for furnace safety control
• Cut-in temperature: 175°F - switch closes to allow system operation
• Cut-out temperature: 205°F - switch opens to prevent overheating
• Direct replacement for Lennox OEM furnace components
• Designed for reliable operation in forced air heating systems

This limit switch monitors the temperature of the heat exchanger or plenum and automatically cycles the furnace blower to maintain safe operating temperatures. When temperature exceeds 205°F, the switch opens to shut down the burner, protecting the system from damage. Once temperature drops to 175°F, the switch automatically resets to resume normal operation.