The fan switch controls the evaporator fan. The fan switch function is the opposite of the light switch. It turns on when the door is closed, instead of off. If a light switch is installed in the fan switch location, poor temperatures will result.
Part Number XP18805 replaces 188-5, 18805, 29-188-5, WR23X163, WR23X192, WR23X361, WR23X5161, WR2M1118