White-Rodgers 50A55-843 Universal Integrated Fan Control

The WHITE-RODGERS 50A55-843 Universal Integrated Fan Control is a universal replacement furnace control board for residential and commercial gas-fired HVAC systems, coordinating ignition sequencing, blower timing, inducer operation, and furnace safety monitoring. It uses 24/25 VAC, 50/60 Hz, and integrates silicon carbide ignition, with relay ratings including 1.5 A valve relay, 6.0 A ignitor relay at 120 VAC, 2.2 FLA / 3.5 LRA for the inducer, and 14.5 FLA / 25 LRA for the circulator; features a diagnostic LED flash code and adjustable blower relay. As a universal OEM replacement, it is commonly installed in gas furnaces, rooftop units, and packaged heating systems, supporting natural gas and LP gas fuels, with common replacements including Emerson 50A55-3797, Honeywell S9200U1000, and ICM Controls ICM280. Key timing and diagnostics include 30-second pre-purge, 5-minute lockout, 17-second igniter warm-up, and a surface-mount design, all operable within -40°F to 175°F.