Description
The Trane SWT3965 is an OEM inducer limit switch engineered to protect your furnace’s draft inducer assembly from overheating. Acting as a critical safety device in the heat exchanger and inducer circuit, this bimetal limit switch monitors flue-gas and inducer compartment temperatures and interrupts the circuit before unsafe conditions can develop.
How It Works
The SWT3965 opens its contacts at 145°F (open-on-rise) to shut down the inducer or burner circuit when temperatures exceed safe operating limits. Once the inducer compartment cools to 115°F, the switch automatically resets (closes), restoring normal operation. This automatic-reset action makes it ideal for residential and light-commercial Trane gas furnace applications.
Key Specifications
- Open Temperature: 145°F (open-on-rise)
- Close Temperature: 115°F (automatic reset)
- Application: Inducer / draft inducer limit protection
- OEM Part Number: SWT3965
- Compatible Brand: Trane
Features & Benefits
- Direct OEM Trane replacement — ensures proper fit and function
- Automatic-reset bimetal design — no manual intervention required after cool-down
- Protects the inducer motor and heat exchanger from thermal damage
- Helps maintain system efficiency and extends equipment life
- Reliable safety shutoff prevents nuisance lockouts caused by wiring or control failures
Application
Designed for use in Trane gas furnaces equipped with a draft inducer blower. Always verify compatibility with your specific furnace model before installation. Consult the equipment service manual for proper wiring, mounting orientation, and torque specifications.







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