E79 Error Message

[MommaL]

Nest thermostat was in the house when I purchased it 2.5yrs ago.   I started getting E 79 messages maybe about 6mths ago.  C wire has power.   Reading all of these posts, I don’t see a solution to this besides Google saying contact an HVAC specialist (what is that going to cost?!).  Seems to me with this many people having the same issue and all of us reporting that there is no issue with the power to the C wire, they should look further into this matter.  Has anyone had help in this regard?  
my solution is looking like perhaps I’ll get a new thermostat that isn’t so “smart”.

[Markjosephp]

Hello MommaL,

Thank you for taking the time in letting us know about your inquiry. I'd be happy to take a look into this for you.

It appears that the common wire may not be properly grounded, so the system uses power sharing but doesn’t get enough energy. Are you still getting the wiring report? If so, please check the battery level for Voc, Vin, and Lin in the power status under technical info.

Also, going over the steps here might help:

1. Remove the C wire and leave it disconnected.
2. Restart the thermostat.
3. Check the air filter. A clog in the air filter can limit how much air flows over the cooling coils. If the clog persists, the cooling coils can freeze and cause the system to shut off.
4. Check the emergency switch and drip pan.
5. Inspect the condition of the HVAC fuses. Occasionally, fuses burn out due to one or more reasons. If the HVAC fuse burns out, the system may cut off the power to the thermostat and cause an E3, E4, E23, E24, E73, or E74 power report.

Please keep us posted on how it goes.

Best regards,

Mark

[Markjosephp]

Hi there,

I'm checking back in. Were you able to do the steps above? I'd be glad to hear from you — I'd like to make sure everything is working.

Best regards,

Mark

[Markjosephp]

Hi MommaL,

It has been a few days since the last reply, and I am going to lock the thread in 24 hours. If you have any questions, please let us know so we can assist you right away.

Best regards,

Mark