Symptoms: 1) Furnace will not turn off once setpoint is reached. We have to go to the thermostat controller and turn the unit OFF. Furnace then does normal shutdown. Furnace comes back on once we turn the thermostat controller back on. 2) A/C will not turn on when setting thermostat to Cool / Fan Auto. Specs: Dometic 5 button Comfort Control Center Thermostat Suburban SF-42 furnace Dometic Penguin II low profile A/C Steps taken so far: Power cycled 12v system Power cycled 120V system Checked fuse for thermostat Replaced the thermostat (I had a back-up unit) Unique events recently: We are in Texas, and had a really cold spell recently with snow. These symptoms began during this cold spell. We also had short rolling blackouts for a few days. Any ideas on things to look at and troubleshoot would be helpful. Thanks in advance!