Code e74 learning thermostat

[Tusia]

Hi there, 

I have a gas furnace and it stopped heating last night.  Today my nest notified me of a wiring problem e74 on my nest learning thermostat. Does anyone have any suggestions. It’s cold up in my “love nest” (name for my home”

[James-YYC]

Try taking it off the wall base plate, and connect it to a USB charger.  It will help for at least a while. 

[Houptee]

Take pic of the wiring on the Nest pull it off the base and show us how it is wired.

Who installed it? And do you have pic of the old tstat wiring before you removed it?

Post pics so we can figure out what is going on.

[Houptee]

e74 means no power on the R wire.

It could be the wire is not inserted in the Nest securely or it could be a problem with the furnace transformer not supplying 24v power on the R wire.

Check the furnace power switch and breaker are on.

Then do a Nest power test as shown in this video and tell us all the readings Battery volts  Vin   Lin 

https://youtu.be/GHkfnRp6Tj8

[MPT]

I had same issue and after powering furnace on and off and resetting the nest, I changed the filter in the furnace. It was dirty and now everything works..

[Jeff]

Hey Tusia,

I just wanted to jump in and see if you saw the responses in the thread and if you were able to try any of the solutions out. If so, did they work for you, or are you still needing some additional help here?

Thanks,
Jeff

[MPT]

I may have replied a little to soon. Although the furnace started to heat after changing the filter, I started getting errors in the furnace. Eventually I ended up changing the filter again to a lower Merv and now all is fine.

[Jeff]

Good to hear, MPT. Thanks for letting us know what worked things out for you.

Tusia, are you still needing some help, or are you back to working 100% with your setup?

Thanks,
Jeff

[Jeff]

Hi Tusia,

I just wanted to check in real fast to see if you saw my reply and to find out if you still needed any help on this. If you're still needing assistance, please just let me know and I'll be happy to continue helping.

Thanks,
Jeff

[EmersonB]

Hi everyone,

@Tusia just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let us know.

I appreciate the help, Houptee and Jeff.
 
Regards,
Emerson