Suburban 525003 RV Furnace Low Air Flow Sail Switch — SF/SFV/SH Series

Genuine Suburban low air flow sail switch for SF, SFV and SH series RV furnaces. It is an air-proving safety device that blocks ignition until the blower reaches about 75% of motor rpm, confirming the combustion wheel is spinning fast enough for a proper air/gas mixture. A common symptom of a failed sail switch is a furnace fan that runs but produces no heat.