OEM Lennox Cad Cell Flame Sensor 14" Leads — 36K53

The genuine OEM Lennox 36K53 is a cad cell (cadmium sulfide) flame sensor equipped with 14-inch leads, designed for use with the Lennox AFII oil burner. This photocell continuously monitors for the presence of a flame during operation. When it detects light from an active burn, its resistance drops and it signals the primary control to keep the oil valve and igniter energized. If no flame is sensed on startup, the sensor triggers the safety lockout, preventing raw oil from accumulating in the combustion chamber.

Common failure symptoms: A failing 36K53 cad cell typically causes intermittent lockouts, nuisance safety trips, or a burner that fires briefly then shuts down. Soot buildup on the cell face, cracked leads, or a degraded photocell can all cause the control to misread flame status, leaving you without heat.

Why OEM matters: Lennox oil burner primary controls are calibrated to the specific resistance and response characteristics of the factory cad cell. Installing the genuine Lennox 36K53 ensures accurate flame detection, reliable safety operation, and full compatibility with your AFII burner assembly — protecting both your equipment and your home.