OEM Lennox Control Board — 59K21
OEM Guaranteed
Same-Day Ship
30-Day Returns
Secure Checkout
The genuine OEM Lennox 59K21 control board is the electronic brain of your Lennox furnace, managing the ignition sequence, blower and inducer timing, safety interlocks, and communication between system components. It reads inputs from limit switches, flame sensors, and pressure switches to safely orchestrate each heating cycle from start to shutdown.
Common failure symptoms: A failing control board can cause no-heat conditions, erratic blower or inducer operation, ignition that won't initiate, repeated lockouts, blank or flashing diagnostic LEDs, and intermittent system resets. Burned traces, blown fuses, or relays that chatter are frequent signs the board has failed.
Why OEM matters: The 59K21 is programmed with the exact ignition timing, safety logic, and component compatibility your Lennox model requires. Aftermarket or mismatched boards can misfire sequences, disable safety features, or fail to communicate with the gas valve and blower. Choosing the genuine OEM board ensures correct operation, preserves built-in safety functions, and maintains full compatibility with your Lennox equipment. Ships same day when ordered before the cutoff.
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