Mars 39028 L240-4 Furnace Limit Switch Open on Temperature Rise 240°F

The Mars 39028 is a Series 390 disc thermostat limit switch designed for quick on-the-job HVAC replacements. Operating on temperature rise, this auto-reset switch opens the circuit at 240°F and automatically closes at 200°F, protecting furnaces and heating equipment from dangerously high operating temperatures.

Key Features:

• Klixon Temperature Code: L240-4
• Open Temperature: 240°F (circuit opens on temperature rise)
• Close Temperature: 200°F (auto-reset)
• Voltage Rating: 120/240V
• Full Load Amps: 10A @ 120V / 5A @ 240V
• Resistive Amps: 25A @ 120V / 25A @ 240/277V
• Pilot Duty: 125VA @ 120/240/277V
• Body Size: 3/4 inch with integral oval flange for common mounting configurations
• UL and CSA listed
• Widest range of replacements in the industry

The Mars 39028 features a 3/4" disc thermostat body with an integral oval flange designed to match the most commonly used furnace mounting options. Its auto-reset design automatically restores the circuit once temperatures fall back to the safe close threshold, making it a reliable overheat protection component for gas furnaces, heat exchangers, and other HVAC heating applications.