Trane / American Standard SWT01275 Thermal Limit Switch - 135°F Open / 105°F Close (3" Insert) 

The Trane and American Standard SWT01275 is a genuine OEM high-temperature thermal limit switch designed as a critical safety component for residential and light commercial gas furnaces. This automatic-reset switch monitors the internal temperature of the heat exchanger or blower compartment, providing a "Normally Closed" (N/C) circuit that breaks upon reaching its 135°F threshold. This safety interlock prevents system overheating and potential damage by interrupting the ignition sequence or blower operation if temperatures exceed factory-safe limits. 

Key Features

• Automatic Reset Safety: Designed to automatically reset the circuit once temperatures drop below the closing threshold (105°F), restoring normal system operation without manual intervention.
• Precision Calibration: Factory-set to open at 135°F and close at 105°F (L135-30F rating), ensuring accurate thermal protection.
• OEM Fit & Finish: Features a standard 3-inch insert length for precise placement within the airflow path of Trane and American Standard units.
• High Life Cycle: Rated for up to 100,000 switching cycles, providing long-term reliability in demanding HVAC environments.
• SPST Configuration: Single-Pole, Single-Throw (SPST) normally closed logic for seamless integration with modern furnace control boards. 

Product Details & Specification

• Part Type: Thermal Limit Switch
• Brand: Trane / American Standard (Therm-O-Disc)
• Opening Temp: 135°F (Open on Temperature Rise)
• Closing Temp: 105°F (Close on Temperature Drop)
• Circuit: Normally Closed (N/C), SPST
• Insert Length: 3 Inches
• Voltage/Current: 120V AC (5.8 FLA / 34.8 LRA)
• Terminal Type: 1/4" Quick Connect
• Reset Type: Automatic

🛠️ HVAC Depot Pro Tip

A tripped SWT01275 limit switch is almost always a symptom of a larger airflow issue rather than a faulty part. Before replacing, check for a dirty air filter, blocked return grilles, or a failing blower motor. If the switch "pops" frequently, it can weaken over time; however, replacing it without fixing the underlying airflow restriction will likely result in the new part tripping immediately.

Cross-Reference

• Superseded Part:

  There are no older Trane part numbers for this specific switch, though it is often searched as SWT1275.

• Legacy / Manufacturing Numbers:

  C340056P13, 36T01B3, 42283, A1730, P13

• Rating ID:

  L135-30F (indicating 135°F trip and 30°F differential). 

Model Compatibility 

This limit switch is compatible with various Trane and American Standard high-efficiency furnaces and packaged units. Below are common compatible model prefixes; always verify the exact fit with your unit's data plate.

Trane Models:

• ADD Models: ADD060C936F0, ADD100R9V5F1, ADD100R9V5F2, ADD100R9V5F3, ADD1D120A9H51BA
• CDB Models: CDB060A936D0, CDB060A936D1, CDB060A936D3, CDB1A060A9361AA
• ADE Models: ADE1A060A9361AA, ADE1A060A9361AB
• 4YCC/4YCY Models: 4YCC4036A1090AA, 4YCY4048C1115AA, 4YCZ6048C1115AA 

American Standard Models:

• ADC Models: ADC060C936C1, ADC100C960A1
• AUD Models: AUD2B080ACV32AA, AUD2D120B9V5VAA, AUD2D120H9V5VAA
• ADD Models: ADD1A060A9361AA, ADD1A060A9361AB
• FCAC Models: FCAC100A50A0, FCAC100A50D1