When your smart control unit starts giving you problems and you guess it is about to split down, the first thing you want to do is go over to it and look for a yellow light that will be on.
What this yellow light means on the smart control unit that I have is that the battery is low and it is time to change it within 48 hours. If you chose to ignore it, your smart control unit will stop laboring and so will your central heating and A/C unit until you go and change the battery. Some people do not even guess that the smart control unit is ran on a correct AA battery. 4 of them to be exact (at least that what it is in my smart control unit). When I first had my smart control unit and the batteries went for the first time, I will never forget the lesson I l earned by wasting a few hundred dollars on calling the local heating and A/C business to send out a certified heat and A/C specialist to repair my central Heating, Ventilation and A/C system. When in fact nothing was wrong with the central heating and A/C unit. It was simply that my smart control unit needed to have the batteries upgraded! After reading that rather extravagant lesson, I am telling almost everyone I guess that has a smart control unit about the batteries in the event they do not guess this. Some looked at me as if I was stupid as they knew about it, and thought almost everyone should. But a few were just like me and had no clue!