It could be a bad thermostat. But I would check for loose wire connections. Remove tstat cover and 2 screws holding it to the wall. Gently pull wires out the hole one at a time if you have to. Double check the small or tiny wire nuts that connect the wires.
Chris & Maria
2012 36RL, Full Body Paint, Dual Awning, Dual a/c, Splendide Combo, Fisher Paykel dishwasher, 6.5kW Onan, Goodyear G614's. 2015 F550 6.7l, 4X4, Lariat, CC, 176" WB, Long Box, B&W Companion