3L09-27 Copeland Comfort Control (White Rodgers) Board Mount Limit Control 220F 2"
3L09-27 Copeland Comfort Control (White Rodgers) Board Mount Limit Control 220F 2"
The 3L09-27 Board Mount Limit Control (White-Rodgers / Copeland Comfort Control) is an automatic reset temperature safety switch designed to protect HVAC equipment, control boards, transformers, electric heat assemblies, and electrical compartments from overheating. Featuring a 220°F fixed open temperature and a 2-inch insertion length, this compact board-mounted bimetal limit switch interrupts the circuit when excessive temperatures are detected and automatically restores operation after cooling, helping safeguard critical electrical components and maintain reliable equipment performance.
Cross-Reference
- 3L09-27
- 3L0927
- L220F
- White-Rodgers 3L09-27
- Copeland Comfort Control 3L09-27
- 74T Series Board Mount Limit Control
Direct OEM
White-Rodgers 3L09-27
Compatible Brands
- White-Rodgers
- Emerson
- Copeland
- York
- Coleman
- Luxaire
- Goodman
- Rheem
- Universal HVAC Applications
Application
Used in HVAC and electrical equipment to:
- Protect control boards from overheating
- Interrupt safety circuits at elevated temperatures
- Automatically restore operation after cooling
- Protect transformers and electrical compartments
- Safeguard electric heat assemblies
- Prevent temperature-related component failures
Related Components
- Board Mount Limit Switch
- Snap Disc Thermostat
- Furnace Control Board
- Transformer
- Blower Relay
- High Limit Control
- Temperature Sensor
- Safety Cutoff Switch
- Electric Heat Control Assembly
Technician Notes
The 3L09-27 is an automatic reset, open-on-rise board mount limit control utilizing a compact bimetal sensing disc and a 2-inch insertion probe. Under normal operating conditions, the contacts remain closed and open when the sensing surface reaches 220°F, interrupting the circuit to prevent overheating. Once temperatures fall below the reset threshold, the contacts automatically reclose and restore normal operation.
The extended 2-inch probe provides deeper temperature sensing than flush-mounted controls, making it suitable for electric heat sections, transformer compartments, blower housings, and OEM HVAC assemblies where precise temperature monitoring is required.
Common Symptoms of Failure
- Equipment shuts down unexpectedly
- Open safety circuit faults
- Intermittent operation
- Repeated high-temperature shutdowns
- Electric heat lockouts
- Control board overheating faults
- No continuity through switch contacts
- Failure to reset properly
- Electrical compartment overheating
Installation Tips
- Disconnect electrical power before servicing.
- Verify the replacement temperature rating matches the original control.
- Confirm switch action is Open on Rise.
- Verify the 2-inch insertion length matches the application.
- Secure the sensing probe properly during installation.
- Inspect terminals for corrosion or heat damage.
- Test continuity after installation.
- Verify operation through a complete heating cycle.
Recommended Inspection Items
- Control board condition
- Transformer temperature
- Wiring harness connections
- Electrical terminals
- Blower motor operation
- Airflow restrictions
- Electric heat elements
- Relay condition
- Ventilation around controls
- Probe insertion depth
