# No power at Thermostat



## xfaith (Jan 11, 2017)

Looking for some help.  Made the mistake of trying to "upgrade" the thermostat to a Nest.  Original equipment was HoneyWell T8001C.

So I wanted to switch out a HoneyWell T8001C with a NEST (1stGEN).  They said it would be easy .

So I verified the wire settings with Nest and then connected it, no power at the NEST, I thought maybe that the NEST was bad, so  I replaced it back with the original Honeywell, now I have no power at the unit.  

I used a multimeter to test the wires and do not show anything from any of the wires.
First one should be the before, and the second one is after reverting back.


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## nealtw (Jan 12, 2017)

[ame]https://www.youtube.com/watch?v=Gc-kq1JUOps[/ame]


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## slownsteady (Jan 12, 2017)

In both pics, I see a wire that is not under the terminal screw. You should correct that. That might be enough of a problem to prevent the Tstat from working properly, but if you are getting No power after you that, check the emergency shut-off switch, check the breaker and - as Neal said - the fuse(s).
Do you have any other zones (Tstats) on the system? And are they working?


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## tk3000 (Jan 12, 2017)

Most of these thermostats use a small transformer somewhere that outputs 24Volts AC. Make sure that whenever you test it with a multimeter to use the right scale and that it is in AC mode.


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## xfaith (Jan 12, 2017)

Its been raining outside (A/C / Heater unit) is outside.  The transformer should be there?  Is that were the Fuse should be also?

When I started I cut power at the circuit breaker for the A/C unit.  I even contacted NEST to verify the wire arrangement before I started this.  I guess I should not have started working on this, I thought it was simple.   

Where would an emergency shut-off switch be?   I dont recall seeing anything.  If it nots raining tonight I will look at the A/C unit.  

Ill look at the video you posted also thanks.
As for the multimeter, I verfied that I had it on AC

Thanks again


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