Amana B1370155 Furnace High Limit Safety Switch – Genuine OEM L120-30 Fixed Temperature

The Goodman Amana B1370155 (L120-30) is a mission-critical safety "brain" designed to protect your furnace from catastrophic overheating. This fixed-temperature limit control monitors the heat exchanger’s internal environment; if temperatures exceed 120°F due to a blower failure or restricted airflow, the switch "opens" the electrical circuit to the gas valve, instantly killing the flame. Specifically engineered for Goodman, Amana, and Janitrol furnace series, this sensor ensures the system remains within safe thermal operating limits. As a genuine OEM component, it features the precise bimetal sensitivity required to prevent heat exchanger warping and ensure your home remains safe from fire hazards. 

Key Features and Function:

• Precision Thermal Management: Calibrated to trip at exactly 120°F and automatically reset when the temperature drops by 30°F (L120-30), ensuring a fail-safe heating cycle.
• Genuine OEM Reliability/Fitment: Features the exact insertion depth and mounting bracket geometry required for a "drop-in" installation in Goodman burner and blower partitions.
• Critical Safety Integration: Directly communicates with the furnace control board to trigger "Limit Switch Open" fault codes, allowing for rapid diagnostics.
• Heavy-Duty Bimetal Build: Constructed with high-grade thermal discs designed to endure thousands of cycles without drifting from the factory temperature setpoint. 

Product Details and Key Specifications:

• Part Number: B1370155 (Replaces B13701-55, 313745, B1370141)
• Manufacturer: Goodman / Amana (Genuine OEM)
• Part Type: Fixed Temperature Limit Control
• Temperature Rating: Open: 120°F | Close: 90°F (30°F Differential)
• Voltage: 24 VAC
• Orientation: Normally Closed (NC)
• Connector: 1/4" Male Quick-Connect Terminals
• Shipping Weight: 0.1 lbs 

🛠️ HVAC Depot Pro Tip: The Airflow Audit

If your furnace is "tripping" on the B1370155 limit switch, the switch is likely doing its job, not failing. Before replacing it, perform a Diagnostic Check on your airflow. A dirty air filter, blocked return vents, or a failing blower motor are the most common causes of high-limit trips. If the furnace fires for a few minutes and then shuts down while the blower is still running, check for a cracked heat exchanger or a clogged A-coil. Always verify the temperature stamped on the side of the old switch matches "L120" before installing the new one. 

Cross-Reference & Compatibility:

The B1370155 is a direct OEM replacement for the following part numbers: 

• OEM Numbers: B1370155, B13701-55, 313745, B1370141, B13701-41
• Therm-O-Disc: 60T11, 313745, L120-30
• White-Rodgers: 3L01-120
• Aftermarket Cross: ClimaTek B13701-55, Mars 39155 

Extensive Model Compatibility List:

Note: Use 'CTRL+F' to search for your specific model:

• Goodman GMS8 Series: GMS80403AN, GMS80603AN, GMS80804BN, GMS81005CN
• Goodman GDS8 Series: GDS80403AX, GDS80603AX, GDS80804BX, GDS81005CX
• Amana AMES8 Series: AMES80403AN, AMES80603AN, AMES80804BN
• Janitrol GMP Series: GMP050-3, GMP075-3, GMP100-3, GMP125-4, GMP150-5
• Janitrol GDT Series: GDT050-3, GDT075-3, GDT100-4, GDT115-5
• GMC Units: Various legacy 80% and 90% AFUE furnace configurations.