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Lennox

OEM Lennox Pressure Switch — 79J08

SKU: LNX-79J08 Brand: Lennox
$24.95 $34.95

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The genuine OEM Lennox 79J08 pressure switch is a critical safety control that confirms proper draft and venting before your furnace's ignition sequence begins. It senses negative pressure created by the inducer motor and, only when correct airflow is proven, closes its contacts to allow the burners to fire — protecting your home from unsafe combustion and flue gas spillage.

Symptoms of a failing pressure switch include:

  • Furnace ignites then shuts down (short-cycling)
  • Inducer runs but burners never light
  • Blinking fault codes indicating a pressure switch fault
  • No heat despite a call for heat from the thermostat

Because the 79J08 is a safety-critical component, using the exact OEM Lennox part is essential — the pressure setpoint is calibrated precisely to your furnace's inducer and venting design. An incorrect or generic switch can trip nuisance faults or, worse, fail to detect a genuine venting problem. Install the factory-matched 79J08 to restore reliable, safe operation to your Lennox furnace.

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 — 79J08?
Yes. This is the factory-specified OEM pressure switch for the Lennox OEM Lennox Pressure Switch — 79J08. 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 — 79J08?
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
HVAC Parts Specialist — Online