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

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I have a Honeywell VisionPro IAQ touchscreen thermostat (model # TH-9421). The right 25% of the screen has no touch response, but visual display is fine. Seemed to happen out of the blue, worked one week, the next week it didn't work. The left 3/4 of the screen has touch response. With the right 25% not responding to touch, can't change temp, humidity, can't even change set up options. Even in setup mode, can't change any values since inputs are on right side of screen. I even got a new thermostat from Honeywell under warranty and popped it in and had the same exact problem...25% of screen on right side is dead to touch. What could be causing this? There are only three pins on the back of the thermostat to connect to 3 wires...everything is there and connected. Could the interface module (down in the furnace room) be causing this? Thanks for any advice or guidance since the HVAC installer is stumped...I want to try to help him solve this.

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Same thing happened to me. I spent 10 minutes on the phone with Honeywell, and they told me to wipe the screen clean. And, believe it or not -- IT WORKED! I was shocked. I thought the guy was just trying to blow me off. But, sure enough.... some times it's just the simple things that work.

Posted on Nov 10, 2010

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    Barbara Nov 18, 2013

    I am happy. Wiping the screen worked for me too!!! Had tried all battery suggestions & none worked. Freezing cold and just about to call a service tech when I read your suggestion. Thank you for your post!!!


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I have not had that problem. But go yo yourhomehoneywellthermastats and the web site has question and answers. Rus

Posted on Nov 18, 2009

  • Barbara
    Barbara Nov 18, 2013

    Wiping the screen worked for me too!!! I was just about to call a service technician. Hurrah!!!


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I do not have the same thermostat but did need to turn my display off when sleeping downstairs near the thermostat. So, I called my utility company that installed the Honeywell Utility Pro Series Thermostat and here is how to do it. It was not in the Honeywell User Manual located at:

  1. Press System – it will blink
  2. Press & Hold Square 3 + 5 at the same time
  3. 120 change with up arrow to 280
  4. 0 = OFF and 1 = ON
  5. Hit Done button
That is it for mine! Hope this helps.

Posted on Nov 20, 2009

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Posted on Jan 02, 2017

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