OEM Lennox Limit Switch — 73W18
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30-Day Returns
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The genuine OEM Lennox 73W18 limit switch is a factory-calibrated safety control that guards your furnace against dangerous overheating. Positioned to sense heat exchanger and plenum temperatures, it opens the burner circuit the moment temperatures climb past a safe limit — most often triggered by reduced airflow. Each switch is set to the exact trip and auto-reset points specified for your Lennox equipment.
Common failure symptoms include the furnace repeatedly shutting off before reaching setpoint, short cycling, delivering lukewarm air, or a complete no-heat condition. A worn or nuisance-tripping limit switch is one of the most common causes of intermittent heating problems, particularly alongside clogged filters or restricted returns.
Why OEM matters: generic replacements frequently carry incorrect temperature ratings and mounting profiles that undermine the protective role of this component. Choosing the factory 73W18 guarantees the right calibration, secure fit, and dependable safety performance for your Lennox furnace, while helping preserve your equipment warranty.
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