| If you know the model number for the Honeywell unit, you may find some help on their website, there they tell you where to find your model number on the unit. Beyond this, the Honeywell site is terrible, most likely you will not be able to find your unit listed. Funny how Honeywell sells thermostats in Lowe, Home Depot now, but do not acknowledge their own part numbers.
The stat usually is timed to tel you when the filter needs changing or cleaning, it is not smart enough to actually know if the filter is dirty.
There may be some sort of reset button on the stat inside, to reset the clock for the filter timer. Look closely at the electronic circuit board or all around the stat looking for a place you can push in with a paper clip or a pencil point.
if you find the stat model number, usually stamped on the inside cover, get back here with it so we can try to find it on the Honeywell site, or you cna can call Honeywell directly , I hear thou they are not much help there either.
Shame, Honeywell is an old well known company, sorry to see thier customer support to be so poor. | 
Where else would you turn with a HVAC problem? Who's gonna take better care of you (or at least talk you down from the ledge)? 
Linear Mode
