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Lennox

OEM Lennox High Altitude Pressure Switch Kit — 18L39

SKU: LNX-18L39 Brand: Lennox
$24.95 $34.95

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Texas CMBL #19328542014
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Govt POs Accepted

The Lennox 18L39 is a genuine OEM High Altitude Pressure Switch Kit built to Lennox factory specifications for furnaces installed at elevated locations where air pressure differs from sea level. This safety switch verifies that the inducer is producing adequate draft before permitting the ignition sequence to begin. If your Lennox system is experiencing repeated pressure switch trips, failure to start, or altitude-related fault codes, the 18L39 kit provides an exact-fit OEM solution.

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

Frequently Asked Questions

Does this Pressure Switch fit my Lennox OEM Lennox High Altitude Pressure Switch Kit — 18L39?
Yes. This is the factory-specified OEM pressure switch for the Lennox OEM Lennox High Altitude Pressure Switch Kit — 18L39. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.
How do I replace the pressure switch on my Lennox OEM Lennox High Altitude Pressure Switch Kit — 18L39?
Difficulty: Medium (20–30 min)
Step 1: Turn off power. Step 2: Locate pressure switch near draft inducer. Step 3: Note tubing orientation. Step 4: Disconnect tubing and wires. Step 5: Remove screw, install new switch. Step 6: Reconnect tubing and wires, restore power.
My furnace shows a pressure switch error. What do I replace?
Furnace LED showing pressure switch error = switch not detecting draft inducer airflow. Try first: clear the rubber tubing to the switch (often clogged with condensation). If problem persists, replace the pressure switch.
Is this pressure switch compatible with Bryant or Payne too?
Many Lennox parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.
Should I use OEM or aftermarket for my Lennox pressure switch?
OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.
How fast does National HVAC Parts ship?
Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.
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Mike Rivera
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