OEM Lennox Furnace Limit Switch — 73K19
OEM Guaranteed
Same-Day Ship
30-Day Returns
Secure Checkout
The genuine OEM Lennox 73K19 is a high-limit safety switch that safeguards your Lennox furnace by monitoring heat exchanger temperature during every heating cycle. Should the temperature exceed the switch's rated threshold, the 73K19 immediately opens the circuit to the burners or gas valve, halting combustion until the system cools to a safe level. This automatic-reset control is an essential safety device found across many Lennox gas furnace and air handler platforms.
Common failure symptoms: A worn or defective limit switch commonly results in short cycling, no heat on demand, a continuously running blower, or a limit-open error at the furnace control board. Years of heat exposure can degrade the bimetal element, causing premature tripping or a failure to open when it should.
Why OEM matters: Every 73K19 is factory-calibrated to a precise trip and reset temperature matched to your Lennox model. A generic replacement with the wrong rating can undermine safety or trigger false shutdowns. The OEM 73K19 delivers exact calibration, a correct mounting footprint, and factory-grade reliability for lasting protection.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days