The Thermostat goes blank most of the time. Have to pull it off the base and replace it to make it work.
Wires in the back have a good connection.
There is low voltage coming in to the wires.
Where is the battery for the unit located at? Could not find one internally.
Once the heating went on by itself when the AC should have been blowing.


James

Operation manual

http://www.totaline.com/dl/P374-1000...Thermostat.pdf

These thermostats were made by Venstar thermostat company. The thermostats always seemed to work well BUT it is possible you may have a bad one.

If the 24 volt circuit is getting to the thermostat as you say then the thermostat may have seen better days. Venstar also had a problem which required a resistor to be installed across the thermostat terminals to correct a (power sharing situation) but you will need to check with Google to see if you can locate exactly what that problem was and why it was caused to start with OR see pages 13 on the link below

http://venstar.com/Support/Installat...nstallRev1.pdf

Power fade or display fade is difficult to determine if not ON SITE so you may end up having to call in a professional for a on site repair.