white-rodgers 1F97-371 trouble

[dwipf]

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 isolated thing.

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.

Thanks

D. Wipf

[Roy Mottola]

[TURTLE]

This is Turtle.

Just install a Blocker relay on the heat mode of the 24 volt circuit and stop it. No big deal at all.

TURTLE

[BGBevill]

Well, I didn't catch the model, serial, or even the brand furnace that the OP has installed this stat on, but I have ran into some models that need an isolation relay to prevent strange things from happening. Not to hard to correct.

Bobby

[Ace]

Call WR they'll help you.

[TURTLE]

This is Turtle.

He can call them but they will tell him the same thing for this bleeding over in heat mode is a common thing with digital thermostats. Now he could try another thermostat to see if he could get by with a new one but your odds are very slim to get it to not bleed over because it is a conflick between the furnace control system and the digital thermostat. I see about 3 or 4 a year like clock work.

TURTLE