there are 3 thermostats on the unit. 2 behind the back panel which are easily accessable, that control the half/full heat by sending current to either one or both of the heating elements. The 3rd is visible thru the port on the front bottom left side of the unit, but only accessable by removing one of the main panels. This is the thermostat that senses air flow and will cut out all heat if there is a blockage in airflow. Also, if this thermostat has failed, the heating unit will not work.
dan wall, December 2006
