The 3L01-300 Snap Disc Limit Switch (White-Rodgers / Copeland Comfort Control) is an automatic reset temperature safety control designed for HVAC, heating, and commercial equipment requiring high-temperature protection. Featuring a 300°F fixed cut-out temperature and 250°F fixed cut-in temperature, this open-on-rise snap disc switch interrupts the electrical circuit when excessive temperatures are reached and automatically resets after cooling, helping prevent equipment damage and unsafe operating conditions.

Cross-Reference

• 3L01-300
• 3L01300
• L300-50F
• 60T11-610026
• White-Rodgers 3L01-300
• Copeland Comfort Control 3L01-300

Direct OEM

White-Rodgers 3L01-300

Compatible Brands

• White-Rodgers
• Emerson
• Copeland
• York
• Coleman
• Luxaire
• Goodman
• Universal HVAC Applications
• Commercial Heating Equipment

Application

Used in HVAC, heating, and process equipment to:

• Protect systems from excessive temperatures
• Open the safety circuit at 300°F
• Automatically reset at 250°F
• Protect heaters, blowers, controls, and electrical circuits
• Prevent overheating damage
• Maintain safe equipment operation

Related Components

• Snap Disc Limit Switch
• High Limit Control
• Fan Switch
• Fan & Limit Control
• Furnace Control Board
• Blower Relay
• Transformer
• Temperature Sensor
• Contactor

Technician Notes

The 3L01-300 is an automatic reset, open-on-rise temperature limit switch. Contacts remain closed during normal operation and open when the sensing surface reaches 300°F. Once temperatures decrease to approximately 250°F, the switch automatically resets and restores circuit operation.

This switch is commonly used in applications requiring high-temperature protection. Before replacement, verify the temperature rating, electrical specifications, terminal style, and mounting configuration match the original component.

Common Symptoms of Failure

• Equipment shuts down on high-limit fault
• Intermittent operation
• Open safety circuit
• Failure to maintain operation
• Nuisance limit trips
• No continuity through switch contacts
• Control board safety faults
• Overtemperature shutdowns

Installation Tips

1. Disconnect power before servicing.
2. Verify temperature ratings match the original switch.
3. Confirm switch action is "Open on Rise."
4. Inspect the mounting surface for proper heat transfer.
5. Check terminals for corrosion or heat damage.
6. Verify proper airflow and ventilation.
7. Test continuity before startup.
8. Confirm operation through a complete heating cycle.

Recommended Inspection Items

• Blower motor operation
• Airflow restrictions
• Electrical terminals
• Wiring harness condition
• Heat exchanger condition
• Control board diagnostics
• Equipment operating temperatures
• Ventilation pathways
• Supply voltage