Ultraviolet control cabinets dissipate real heat from ballasts and ignitors into a largely sealed enclosure. A blinded filter is the usual first cause of a cabinet running hot: airflow falls gradually, so temperature-related faults appear long before anyone suspects the filter. Replace on a routine interval rather than on symptoms. This is the 230 V fan that cools the ballasts. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.