Heater/AC delayed start
So for the past couple of weeks, I have noticed that heater/AC are not starting right away. That is, before when setting the thermostat I would hear a click the moment it was set above (for heating) or below (for AC) the room temperature. The AC started immediately and the heater within a minute or two.
Now, I move the thermostat temperature and I hear nothing. If I leave it be, the heater or AC will eventually turn on after 5-10 minutes.
Some background: I cleaned the filters (electronic) about two months ago. Also, about a year ago I noticed that the AC/Heater were short cycling. I went into the attic and noticed that one of the ducts had come loose. I fixed it and the short cycling issue was gone.
I have a digital thermostat (whose brand escapes me) with a number of controls (including a timer, day/week scheduling). Not sure how long the timer has been in place as it came with the house.
Anyway, before I go back into the attic, I am wondering whether folks have any ideas here. Could the thermostat have some kind of setting that I accidentally set for a delayed start? Could it be wiring? A duct?
What do you guys (and gals) think?