Hello, I purchased a 1F97-371 thermostat and installed it myself according
to the instruction manual. It replaced a mechanical thermostat. I have a
heat only, cool only, & heat/cool single transformer system.
I tested it and all functions are working properly, it heats, cools, runs
the fan, etc. Over the summer, the AC worked fine
But, I seem to have some problem.
Recently, the weather here has allowed me to turn off heating and cooling
and I noticed something strange. One evening I heard the furnace fan
engage for about 5 s, stop for 2 s, and then repeat continuously. Also, I
should say the the fan doesn't operate "full blast". It sounds like it is
just starting and then it shuts off.
I pulled the thermostat off the wall plate and it stopped. Put it back on
and it started the fan cycling again. So I know that the thermostat is
making the fan come on. The thermostat is set OFF.
So, I pulled it off the wall, pulled the batteries and let it set for 24
hrs. Thinking that this would reset it.
I put it back on the wall and, NO cycling, good.
But, about 2 weeks later, still having not used the heating or cooling, it
started this cycling again. So, now I am annoyed. Clearly this is not an
I pulled it off the wall, pulled the batteries and let it reset again for a
couple of days and now it is not cycling.
My hunch is that the cycling is the thermostat using the "phantom power"
mode and this is pulling enough juice to momentarily kick the fan on. But
what do I know?
Anyway, what do you suggest.