Nest Rh and C Wire Intermittent Power

[jrshelt10]

I installed a Nest thermostat on my heating/cooling system last year. I had no C wire and had a myriad of furnace issues because of it. Finally installed the Venstar "Add a Wire" based on many reviews. Worked at first but now I get intermittent loss of power to either the Rh or C wires. I checked all the wiring and it'd all good. I even checked it at the control board and voltage drops off occasionally. Other times the Nest works just fine.  Furnace seems to be working otherwise (not too cold in house) so just wondering if anyone else has this experience. I could get bad wiring or a bad board if the fault was constant but coming in and out with no intervention has me confused. 

[Ryan_G]

Hi jrshelt10,

Thanks for reaching out and we're sorry for the delay.

Based on the details from your post, it looks like the HVAC unit is not delivering stable power to your Nest Thermostat. You've mentioned that you tested the voltage from the main terminal block and it is dropping. You could check the fuse first and then try to charge the thermostat using a USB charger and check if it's going to have a stable power.

Let me know how it goes by replying to this thread.

Best regards,

Ryan

[Ryan_G]

Hey jrshelt10,

I just wanted to follow up and see if you're still in need of help? Please let me know, as I would be happy to answer any questions you may have.

Best regards,

Ryan

[jrshelt10]

Hi Ryan G,

Thanks for the reply. I replaced the wiring from the furnace to the thermostat and it appears to have fixed the issue. 

[Ryan_G]

Hey jrshelt10,

Thanks for visiting the Google Nest Community. 

Since this thread hasn't had activity in a while, we're going to close it to keep content fresh.

If you have additional questions, feel free to submit another post and provide as many details as possible so that others can lend a hand. 

Hope this helps!

Kind regards,

Ryan