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The genuine OEM Lennox 87W64 (factory part 103324-06) is a 50-amp, three-phase SCR (silicon-controlled rectifier) control board designed to regulate electric resistance heat in compatible Lennox commercial rooftop and packaged units. It electronically switches power to the heating elements, providing smooth staged output, precise supply-air temperature control, and less mechanical wear than contactor-based staging.
Common failure symptoms: A failing SCR control can leave heat stuck off or stuck on, cause elements to cycle erratically, trip high-limit safeties, or produce uneven discharge-air temperatures. Nuisance breaker trips, a burnt-electronics smell, visible scorch marks, or fault codes at the unit controller all point to a control that needs replacement.
Why OEM matters: Lennox builds the 87W64 to exact 50-amp, three-phase ratings and control-signal timing for their equipment. A genuine OEM board guarantees correct gate triggering, thermal capacity, and connector fit — protecting your heating elements and main control from the timing mismatches and premature failures common with generic replacements. OEM installation keeps the system within factory specifications and helps preserve warranty coverage.