Ultraviolet control panels dissipate real heat from ballasts and ignitors into a largely sealed enclosure. Cooling failures present as intermittent, temperature-dependent shutdowns rather than as a clean fault, so airflow parts are worth replacing on condition rather than on failure. This is the 119 × 119 mm guard for the cabinet fan. It is a safety component as well as a mechanical one — it keeps cabling and fingers clear of the impeller.