1  | Belt cleaning/cooling fan  | 
2  | ITB  | 
3  | Thermostat  | 
A small fan both cleans and cools the area on the side of the ITB where the fusing unit generates heat. A thermostat [3] monitors the temperature around the ITB unit. This is a safety device. If the area around the ITB overheats, the thermostat will blow and shut down the system.