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Lennox

OEM Lennox Pressure Switch — 33J20

SKU: LNX-33J20 Brand: Lennox
$24.95 $34.95

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Texas CMBL #19328542014
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Govt POs Accepted

The genuine OEM Lennox 33J20 pressure switch is a critical safety control that verifies proper venting and combustion airflow before your furnace's ignition sequence begins. It monitors the negative pressure created by the draft inducer motor and closes to signal the control board that it is safe to light the burners. When it fails to confirm airflow, the furnace will lock out to protect your home.

Common failure symptoms include a furnace that ignites but shuts down shortly after, a blower that runs without heat, repeated lockouts, or diagnostic fault codes indicating a pressure switch fault. Blocked vents, a weak inducer, or a stuck or corroded switch can all trigger these issues, and a faulty 33J20 will prevent the furnace from firing entirely.

Why OEM matters: Lennox pressure switches are calibrated to a specific trip point matched to your furnace model's venting design. Installing the exact OEM 33J20 ensures the switch trips at the correct pressure, preserving the safety interlock and preventing nuisance lockouts. Generic aftermarket switches with the wrong set point can cause intermittent operation or fail inspection. Choose the factory-specified part for reliable, code-compliant performance.

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 Pressure Switch — 33J20?
Yes. This is the factory-specified OEM pressure switch for the Lennox OEM Lennox Pressure Switch — 33J20. 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 Pressure Switch — 33J20?
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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