What causes an erratic temperature display? The temperature jumps up and down.
A digital kiln measures the firing chamber temperature with a thermocouple, which is a metal or ceramic-sheathed rod that extends into the firing chamber.
When the thermocouple is about to fail, the temperature display often becomes erratic or inaccurate. If the temperature is off by 45 degrees F. or more, replace the thermocouple.
Some brands of controllers give a temperature reading of the controller’s circuit board itself. (This feature is not available on earlier controllers or on Paragon’s Sentry Xpress 3-key series.)
With the kiln at room temperature, check the electronic circuit board temperature. (Paragon’s Sentry 2.0: Select ELEC under Options.) If ELEC shows room temperature, then the board is okay. If the ELEC temperature is way off from room temperature, the problem is a board instead of a thermocouple.
An erratic or inaccurate temperature display can also be caused by a loose thermocouple connection, a bare spot on the thermocouple wire touching the kiln case, or the thermocouple touching the kiln case.