The most probable reason for this is usually a bad heater element, but at times it can be caused by a failed main blower or a damaged circuit board. Check to make sure that with the drawer removed and the unit turned on, that there is good air-flow in the chamber.
You can unplug the sterilizer, remove the back and check the ohms on the heater element.

Please call us now at 800-762-1586 This Model has been discontinued

Thank you –
~Shlomo Savyon
1-800-762-1586
Your Sterilizer expert