My furnace shuts off when I set the temp below 66. Is it thermostat? Can raise temp and reset and service is restored.
The problem could be the thermostat or you have the wrong size of filters. You can contact the thermostat company to come and check it out and fix the problem.
Check the filter. We had a similar problem, turns out - the wrong size filter was installed.
It sounds like it is freezing up
Raise the temp on it you want heat