We have been in a newly built condo for just one year and have had no problem with the air/heat. Two days ago for the first time the Carrier Digital Thermostat starting blinking.

It blinks with a blank screen and then blinks and you can see the digital info then back to a blank screen. Yesterday it starting working again. The screen display was normal and no blinking. This morning it starting blinking again. And of course not operational. Does this mean the thermostat needs replacing?

Some stats require a battery to maintain memory. Check your manual or unit to see if you have a battery. I'd replace the battery before I'd think about replacing the stat.