topic Re: E74 code no power to rh wire. in Nest Thermostats

E74 code no power to rh wire.

Steveoarroyo — Wed, 19 Jan 2022 04:16:03 GMT

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.

Re: E74 code no power to rh wire.

MelbaDT — Tue, 25 Jan 2022 03:09:34 GMT

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

Re: E74 code no power to rh wire.

MelbaDT — Fri, 28 Jan 2022 05:37:23 GMT

Hey there,

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

Best,

Melba

Re: E74 code no power to rh wire.

MelbaDT — Sat, 29 Jan 2022 08:33:06 GMT

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

Re: E74 code no power to rh wire.

Jedidiah88 — Mon, 14 Feb 2022 22:13:27 GMT

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

Re: E74 code no power to rh wire.

M18nest — Fri, 18 Feb 2022 23:59:25 GMT

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?

Re: E74 code no power to rh wire.

Soon2bpostGoogl — Thu, 02 Jun 2022 23:01:50 GMT

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.

Re: E74 code no power to rh wire.

Michelledew — Sun, 17 Jul 2022 23:54:13 GMT

Me.too.. how do we resolve this issue

Re: E74 code no power to rh wire.

LourdesA — Tue, 23 Aug 2022 15:40:09 GMT

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

Re: E74 code no power to rh wire.

homesmart — Thu, 01 Sep 2022 01:38:40 GMT

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

Re: E74 code no power to rh wire.

Speers — Sat, 03 Sep 2022 22:47:34 GMT

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.

Re: E74 code no power to rh wire.

504creole — Sun, 11 Sep 2022 22:46:58 GMT

I need help too. All troubleshooting complete.

Re: E74 code no power to rh wire.

Mel917 — Mon, 12 Sep 2022 14:24:20 GMT

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

Re: E74 code no power to rh wire.

Mel917 — Mon, 12 Sep 2022 14:27:06 GMT

Google, I don’t care that I received a reply badge! I need my a/c to work.

Re: E74 code no power to rh wire.

504creole — Mon, 12 Sep 2022 14:48:24 GMT

Try moving to Rc.

Re: E74 code no power to rh wire.

Yeagera55 — Tue, 20 Sep 2022 10:50:46 GMT

I am also having the same issue help!! I don’t even know who the hire to come help either

Re: E74 code no power to rh wire.

504creole — Tue, 20 Sep 2022 11:38:55 GMT

Nest support chat won't help unless the error is active. The problem with that is you may not realize the error is there or can catch it in time to get to nest. The error happens randomly and the duration is also random in my experience.

If you've tried both R terminals to rule that out and made sure your wire connections are good and it's still happening then make sure your drain pipe isn't clogged and tripping the float switch/overflow switch.

Re: E74 code no power to rh wire.

Xinyuwang — Tue, 20 Sep 2022 16:54:01 GMT

May I ask have you solved this issue? This happened to me either.

If you solved, may I ask how you solved?

thank you! Cynthia

Re: E74 code no power to rh wire.

Xinyuwang — Tue, 20 Sep 2022 16:57:53 GMT

tried to move wire to RC but shows e73 issue.

Does this mean i need to buy a new one? Is that someone please help! Winter is coming and it is so cold in Canada.

Thank you!

Re: E74 code no power to rh wire.

504creole — Tue, 20 Sep 2022 17:03:50 GMT

Still monitoring but I think I have. I even bought a new thermostat and swapped everything out yet it still occurred. At that point I realized it was in the house and not with Google/Nest. It's weird though that so many people have and are experiencing this same thing "at the same time".

My issue seems to be with that float switch. I had a tech check my AC but he missed that. I called back and another tech came out. Checked voltage, wiring, etc. Took it all apart. Then he got to my drain pipe and realized there was water in it. Not much tho as my nest was working of course when he showed up. But he came to the conclusion that it was intermittently filling up and tripping the switch. Glad that works! Don't need a leak in my ceiling. Lol.