Question about Honeywell Electronic Programmable Heat/Cool Thermostat - CT3300A100 Heater

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Honeywell thermostat - screen flashes and temp setting changes

We have a honeywell thermostat and I do not have a manual. The only numbers that I can find on it are 97-5207 REV. The screen has flashed on an off for the last 2 days. Today I went to adjust the temperature by 2 degrees since it is only going to be 8 degrees tonight. The screen changed and said that it would hold the temp at 48 or 56 degrees. The temperature numbers keep changing. I would like to find out if this means that I am in need of a new thermostat, or if there is a way to fix it or if there is potentially something wrong with my furnace? A few minutes ago, the thermostat said 68 degrees and now it says 81 degrees. Please help.Will this confuse the furnace and have it running at a higher temperature? Now it has dropped back down and says 68 degrees

Any assistance that you can offer is greatly appreciated.I just want to be sure that the furnace will keep working. .
Usually when I feel the air coming out of the vents, it is just barely warm. However, I have at least 2 vents where the air is quite hot...Is this a concern?
Thank you in advance Robyn

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Hi and welcome to FixYa,

The Honeywell thermostat that you posted could very well be part of an intricate system that involves the furnace, the gas supply, a controller, ducting, vents, blowers, sensors and the thermostats as just the user interface.

While it would be easy to open up the thermostat and try to figure things out, it may be to your advantage to seek the services of an on-site technician.

An error while trying a quick fix may result in a totally inoperative heater system that would of course be detrimental to you.

Good luck and Thank you for using FixYa.

Posted on Dec 05, 2008

  • Louie  Role
    Louie Role Dec 12, 2008

    Hi again,

    Any updates or developments so far?


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If it is a battery model, to reset, remove the battery.

I see if I can find a manual.

Posted on Dec 05, 2008



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