Chronotherm IV Plus Problem

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  #1  
Old 04-06-09, 06:40 PM
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Chronotherm IV Plus Problem

Hi all,
I'm trying to upgrade from a Chronotherm III to the above T-stat (Honeywell T8625D2004), but have run into a problem. The A/C is continuously turned on (regardless of the System setting: Heat, Cool, Off, Auto or the temp setting!!). My furnace guy finally found that the Y1 terminal was always at 24V.

Is this a common failure mode for these items? Is there anything I can do to solve this short of pitching it and buying another one?

Thanks for your help, Tom
 
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Old 04-06-09, 08:51 PM
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Originally Posted by Tom Tucker View Post
to the above T-stat (Honeywell T8625D2004),
You got the correct model #? I am not able to find anything.

My furnace guy finally found that the Y1 terminal was always at 24V.
At the t-stat?

Is this a common failure mode for these items? Is there anything I can do to solve this short of pitching it and buying another one?
I'd say no. But it can happen, and I've never came across this myself.
 
  #3  
Old 04-07-09, 05:52 PM
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Jay,
Thanks for your reply. Sorry -- It's a T8624D2004. I connected the R and common wires to power the unit for testing. I'm measuring 28VAC between the red and common wires using a digital multimeter, but nothing between the red and Y1 (during cool call), W1 (during heat call) or G (when fan is set to on). I get 28VAC between the common and W1, Y1 and G. I do hear relay clicks when I change settings. What are the expected voltages?

Thanks, Tom
 
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Old 04-07-09, 06:44 PM
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Originally Posted by Tom Tucker View Post
but nothing between the red and Y1 (during cool call), W1 (during heat call) or G (when fan is set to on).
That's OK.

I get 28VAC between the common and W1, Y1 and G. I do hear relay clicks when I change settings.
That's correct reading.

With stat off, you should should not read anything between W, Y, G and C.
 
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