OEM Lennox Defrost Control Board — 18M23
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The genuine OEM Lennox 18M23 defrost control board is the electronic brain that manages the defrost cycle on your Lennox heat pump. It monitors coil temperature and run time, then reverses the system to melt frost and ice from the outdoor coil so efficient heating can continue in cold weather. As a direct factory replacement, the 18M23 restores precise defrost timing and reliable system sequencing to your Lennox unit.
Common Failure Symptoms
- Outdoor coil ices over and never clears
- Heat pump fails to switch into or out of defrost
- Auxiliary/emergency heat runs constantly
- Erratic operation, no outdoor unit response, or blank diagnostics
A failed defrost board often shows up as reduced heating capacity, excessive ice buildup, or a spike in electric bills from constant strip-heat operation.
Why OEM Matters
Defrost boards are programmed to model-specific timing and sensor logic. Universal or aftermarket boards can misread defrost intervals, causing icing or wasted energy. The OEM Lennox 18M23 is built to your system's exact control specifications, guaranteeing correct terminal layout, dependable defrost management, and proper integration with your Lennox equipment.
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