E74 code no power to rh wire.

[Steveoarroyo]

Just installed a new nest gen 3 learning thermostat on 01/14/2022 which went without a hitch and worked fine until this morning. My house was cold and my nest thermostat did not show any temperature. It had a e74 code, no power to RH wire. Reset my  power and it came on for a short but it failed just minutes later. Tried again and it did not work at all with the same code. It should not be doing this and I have seen other postings with this issue. I had to install old thermostat to get my heater to work. There is no reason or excuse why this thermostat which is not cheap should present these issues. Would like to know if there is a solution for this problem since I am not the only one experiencing this problem.

[MelbaDT · Accepted solution]

Hey Steveoarroyo, 

Sorry to hear about your experience but thanks for posting. 

Just to confirm, when you tried connecting back your Nest thermostat, did you ensure that the wires are properly seated? If unsure, could you make sure of the following:

• Check that each wire is fully inserted into its connector and that every connector with a wire is down as shown.
• Check that each wire has ⅜ inch (6mm) of exposed wire.
• Turn the power to your system back on and check to see if your thermostat is working.
• Check that each wire is connected properly to the system board.

I also suggest that you check on this link for more troubleshooting suggestions. 

Best,

Melba

[Jedidiah88]

I am having the same issue with the RH wire. I am getting an E74 code. Please help

[Michelledew]

Me.too.. how do we resolve this issue

[Lisa54]

I am having the same issue as well.

[Lisamarie129]

I'm having the same problem. Did you ever figure this out?

[Lisa54]

They referred me to a technician that is coming out tomorrow to look at it. 

[L27]

Did the technician fix it? What did they do? How do you even find a technician that can help? Same issue e74 Rh wire and I'm on solar so not sure about this or where to turn for help (except to a community like this)

[Lisa54]

The tech came out and diagnosed it. He said that there was no power going from my furnace to my thermostat. We corrected that issue and it’s now working.

[L27]

Do you mind telling me how much you paid to fix the issue? TIA

[Rodtennell23]

How did you provide power? What did you change?

[Amcunniff]

I am having the same issue and am on solar as well. My house has 2 zones and the other works fine. 

[Speers]

Same issue.  I haven't touched my thermostat nor its wiring and I'm getting the E74 error message.  No idea why . . .I only have a furnace connected, not A/C.

[dBurt]

Exactly same with me. No AC. Havent touched a thing. Very obvious now since it's cold

[dBurt]

Again. Same problem. Correction. I have 3rd generation, not 2nd

[AlexSchindler]

not working. same issue as everyone below. I have now spent more on trying to make this garbage work than the item itself cost, and my home now has no heat in winter. what a disastrous choice to buy a Google product for something that actually matters. 

[dBurt]

I have 3 nest, 2nd gen thermostats in 3 different zones. All 3 go out at the same time several times per day and go back on by themselves in 5 to 30 minutes. I've been having this problem since they were installed over a year ago. Recently it's been happening more frequently and lasting for longer periods of time. What should I do? Thanks

[DanBor]

I am having a similar problem. I get an E74 error message several times each day. It usually lasts about 30 seconds and then it goes away. Any thoughts on what might be causing this? BTW, it happens in both heating season and cooling season. This has been happening for several months. Any thoughts?

[L27]

All, I figured out what happened to my furnace, not sure if this is helpful. The problem with my situation was the safety door to the furnace somehow came loose and the whole system stopped connecting  to power. This tripped the Rh power error message so check the safety features and doors which triggers the furnace switch. Good luck 

I wanted to come back to this community to follow up since my issue was fixed in case this might help someone else.

[kenster]

Same issue, furnace safety door switch wasn't depressed properly.

[dadutzit]

We did everything but still show no power. Never have this issue in the last 6 years until this month on both of the Nests... ???

[MaryS]

I have the same situation. I checked my heater.  Found the furnace fire stops (heat is still on). after about 3 minutes the furnace fires again.

[Iambrewster]

I have same with Sue and tried all these fixes but to no avail , who can help me

[Derekk]

Wife’s are connected properly. Says no internet connection.

[Derekk]

Wires connected properly!

[Kmfoster79]

I’m having the same issue. Worked fine for years until recently. HVAC tech came out last week and of course everything was working fine and he couldn’t find anything wrong. It’s now happened twice since last Wednesday. Seeing all these issues reported leads me to believe there’s a problem with the thermostat or the mounting plate. 

[Dakota62]

If you have a partially draining drain, it will work until it backs up(assuming you have a float switch). Most do these days. In 90% of cases you just need to clear the drain

[MelbaDT]

Hey there, 

Just checking back in — do you still need help with your Nest thermostat?

Best, 

Melba

[AngelaC]

Yes still need help. Haven’t touched these wires in ages - e74 - verified it is seated & down.

[Darkon73a]

Hello.  I had this same issue and all wiring is fine in the breaker box and in the wall.  Issue persists.  Need help!!!

[dBurt]

Yes

[MelbaDT]

Hi, 

Since it's been since this thread was last updated, we'll be locking it if we won't hear back from you again within a day. Should that happen, feel free to create a new one should you have more questions or have other concerns in the future. 

Thanks, 

Melba

[Khays213]

I am having the same issues e74 saying no rh power.  However I have two other thermostats on the same system non nest brand and they are working fine so this is a nest specific issue. Do I have bad units?? I have two and it happened at the exact same time 

[Amcunniff]

Mine just happened today - I have two heat/cool zones and solar. Everything else in the house is fine. The HVAC is new last year. 

[M18nest]

My Nest was installed in September and worked fine in AC mode through January. It worked in Heat mode until today (February 18) when I returned it to AC. It was working when I left home. Upon returning it was offline. The thermostat had an E74 code. I checked the circuit box and reset the breakers. Nothing changed. The Rh connection appears good. What is happening? Do I have to reinstall the old thermostat? 

[Soon2bpostGoogl]

Same thing happened to me.  And my thermostat is less than two years old.   Technician came out and verified that the thermostat was defective and was not relaying to my unit properly.  

The technician verified all of the wiring and that it was wired correctly but Thermostat was not sending of Romero on to relay and said I would need a new unit.

if Google does honor an exchange for a less than two year old thermostat, I will be switching brands.  Already phasing out Google products because of issues such as these.  As for thermostats, EcoBee and Honeywell seem to have good overall track records and back their items better.  So if you change , I would look to those companies.  Especially, Honeywell.

[LourdesA]

I keep on having that message every so often for no reason also …. So disappointing!!! 

[homesmart]

I have had my nest installed for almost two years, and now today I'm getting an e74 RH wire that isn't connected.  Never had this error message and can't get back to the menu.  help

[504creole]

I need help too. All troubleshooting complete.

[Mel917]

I’ve gone through all of the checks and still getting no Rh connection and not connected to WiFi. Please help.