If you're talking about the fan switch, the original application used resistors between two of the "connectors" on the switch. This is a car switch but it shows the resistors.
Low speed routed current through both resistors, mid speed routed current through one resistor, high speed was a direct connection between wires. It's possible that someone intended for a new switch to be used with a blower motor with three windings to provide three speeds without resistors. This is a common strategy with bus and motorhome heaters.