The Vent Switch is an OEM replacement part for Bosch range hoods. It is an electronic control device located inside the range hood that regulates the internal vent and fan functions. Causes of a faulty vent switch can include long-term use in high-heat cooking environments, damage from accidental spills or impacts, or normal component degradation over time. Symptoms include: Failure of the fan or vents to engage during cooking   Variable or inconsistent fan speeds that don't adequately vent smoke Electrical shorting or sparking noises from within the hood control unit This genuine Bosch replacement part is also compatible with Thermador, Gaggenau, and some Kenmore range hood models.00189968 (AP2825671) replaces 00413770, 189968, 19-12-144, 413770, 948312, AH3440924, EA3440924, PS3440924, PS8698805.