On Fri, 25 Dec 2015 16:25:21 -0500, Tekkie®
wrote:

System light is not coming on and I have already replaced the batteries.
The unit shows the time and -AC fails to turn on the furnace.


--

Did you pay the electric bill? -AC usually means there is no power to the
furnace to get commands from the thermostat.

My Christmas gift to you...

.... global warming electricity?