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Lennox

OEM Lennox SCR Control Board 75A 3-Phase — 87W66

SKU: LNX-87W66 Brand: Lennox
$39.95 $54.95

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The genuine OEM Lennox 87W66 (factory part 103324-08) is a 75-amp, three-phase SCR (silicon-controlled rectifier) control board used to modulate electric resistance heat in compatible Lennox rooftop and packaged units. By electronically switching power to the heating elements, it delivers smooth, staged heat, tighter supply-air temperature control, and reduced wear compared to mechanical contactor staging.

Common failure symptoms: When this SCR control fails you may see heat that will not energize or will not shut off, elements cycling erratically, tripped high-limit switches, or inconsistent discharge-air temperatures. Nuisance breaker trips, a burnt-electronics odor, visible scorching, or fault codes at the unit controller indicate the board should be replaced.

Why OEM matters: Lennox manufactures the 87W66 to precise 75-amp, three-phase amperage, phase, and control-signal specifications for their equipment. A genuine OEM board ensures correct gate triggering, thermal ratings, and connector fitment — safeguarding your heating elements and unit control against the mismatched timing and early failures typical of generic parts. Installing OEM keeps your system within factory specifications and helps maintain warranty coverage.

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 Control Board fit my Lennox OEM Lennox SCR Control Board 75A 3-Phase — 87W66?
Yes. This is the factory-specified OEM control board for the Lennox OEM Lennox SCR Control Board 75A 3-Phase — 87W66. 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 control board on my Lennox OEM Lennox SCR Control Board 75A 3-Phase — 87W66?
Difficulty: Advanced (1–2 hrs)
Step 1: Turn off breaker. Step 2: PHOTOGRAPH all wire connections before touching anything. Step 3: Label each wire with tape. Step 4: Disconnect all wires, remove old board. Step 5: Mount new board, reconnect all wires matching your photo exactly. Step 6: Restore power and test all modes. Exact part number match is critical.
My HVAC system is completely dead. What could be wrong?
Completely dead HVAC (no LED on board) = failed control board or blown fuse. Check board fuse first (3A or 5A, costs $1–$5). If fuse is good and board has power but no LED, board is dead. Always photograph wiring before replacing.
Is this control board 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 control board?
OEM essential. Control boards are model-specific with precise firmware and connector layouts. Aftermarket boards rarely match all functions and can cause intermittent failures or safety issues. Always match the exact OEM part number.
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