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Comm Failure Error on TS40B Wall Display

I have got a “Comm Failure” error on my AC control panel. The control panel is a Ztech TS40B wall display panel. The symptoms and the solution were found in the following forum thread: Receiving “Comm Failure” message, no heat.

Here is the quote from that thread:


I have a TS40B Wall Model Thermostat from Beutler. Right now my aircondition/heating wall display is showing ‘comm failure’. Can anyone tell me what this is and how to reset? Right now, nothing is working, Heat, Fan, SmartVent…I would be thankful for any insights.

I was able to find the User manual online, and it makes reference to “Hold Settings”, which was the last button to the right. Which is now no longer there or even indicating its available. The system shows it’s off, with no option of turning it back on to “run” or “hold”.


Update: Note to all who may run into this issue with their own TS40B Wall Model Thermostat. Turn all of the power off, flip your main breakers. Initially, I tried just flipping the breakers for the HVAC, but nothing changed. I decided to flip the main breakers; everything came back online exactly as it was before.

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  1. Wick
    October 2nd, 2012 at 19:09 | #1

    Thank you so much!! Problem solved!!

  2. Doug
    August 1st, 2013 at 07:14 | #2

    Carrier split system, indoor blower keeps running non stop even when the TSTAT is turned off and fan switch is in auto position.

  3. Doug
    August 1st, 2013 at 07:16 | #3

    Can the TS40B be replaced with a triditional thermostat?

  4. Ernest Abe
    April 27th, 2015 at 13:10 | #4

    Note to all: The “Solution” mentioned above is what rebooted my upstairs Z Tech TS40B Wall Model Thermostat. Since I have a 2 story house with dual zones, the downstairs was still working while the upstairs unit had the “Comm Failure.”
    Flipped the main breaker OFF for about 60 seconds, and turned on and the system worked, again.
    (You’ll have to reset all your digital clocks, but that’s a small price to pay.)

  5. BillyRobMotzie
    December 30th, 2015 at 12:59 | #5

    Yes, thanks so much for the info! I pulled the t-stat off of the wall, opened it, blew out any dust, then reseated it, didn’t work. Did what you recommended and it’s all good! Saved me $, was gonna replace it. Thanks again!!

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