The thermostat (separate for gas and electric operation) can certainly stick or otherwise fail or could possibly become dislodged. If dislodged, it would be reading outside temperature and would go full cole.
John W. Irwin
2005 Classic 28 "Sabre-Dog III"
2013 Silverado 2500HD Duramax/Allison LTZ
WBCCI #9632, TAC TX-10