E103, yet again. No changes to wiring and I'm sure the unit has just gone bad...again.

[H8_Nest]

Do these crummy things ever last more than a year?

This is the 2nd time one of these thermostats has crapped out and started sending the e103 code.

And yes, I know I have to call someone out, but I also know that they won't find any wiring changes, because there haven't been any, and they won't find that anything has worked loose, because it hasn't, but, because it has been just over the timeframe of the warranty, I'll have to pay to replace this silly thing again.

I am for sure going back to analog, but I would like to have some comfort between now and whenever my AC guys can come and charge me to tell me the Nest unit is bad...again.

I've done a restart and I can get the unit to blow cold air for 10 or 15 min, then the equipment change/wiring message pops up again (exact behavior as the last time it went out).

I've done a reset and couldn't even get the fan to blow in the setup.

Is there some way I can get this thing to run the AC for at least a night and a day until I can get someone to come and verify that it is trashed?

I'm open to anything that will make the thermostat run, even if it destroys the Nest unit - it's gone as soon as I can swing it.

[Patrick_Caezza]

The Nest E103 error code means the thermostat has detected an overcurrent event on the Y1 wire. This normally means that something is wrong with your system and not the Nest.

One of the most common failures that can cause the E103 error is the contactor in the outdoor unit is failing.

[Sheri1]

Yes, that is what happened with mine.  It was also two other things he replaced in the AC unit, one was dead the other was going.  If I had my choice I would rather have replaced the Nest Thermostat.  It was 10% cheaper!

[Noname5466]

I actually had the same thing happened to me and it’s the nest thermostat

[techjedi85]

Same error code and same exact issue, contactor on outdoor unit. Tech said it was the second one he had fixed today.  

[Mkarthik564]

How much does it cost for HVAC service?

[Tha_lukester]

Yup, same here. 
was warranty as it was all new (nest and AC 1-2 yrs old). 
contractor kept saying it must be the nest. Pressed him to keep checking as I didn’t think so. Finally I FOUND THIS THREAD, and recommended looking at the contact (not knowing what this was). Eventually he used another thermostat to confirm, and the system didn’t work. Replaced the contact, Nest took a good 5 minutes to charge the unit before working, then worked perfectly. 
contractor apologized more than once, and said he learned something today. 
thanks to this page! 

[Marie36]

Disagree my old unit A/C and Furnace was replaced last year with a new high efficiency we had an issue initially testing A/C    I turned on the air last night immediately received the 103 error.  There is nothing wrong with my equipment or all new wiring.  It’s the stupid Nest Thermostat!

[Jdk]

My issue was the cable that went from my furnace to the outside air compressor. Apparently because it can be exposed, mice and weed whackers can cause a break into that cable and cause a short which is one of the things that can cause an e103 error. You should check to see if there's any damage on that cable first before blaming the nest. 

[Marie36]

Haven’t had my first cut this year it happened to reach 85 very unusual for this time of year in NE. Ran fine all winter with heat.  Turned the Air on to cool down the house before bed that’s when the e103 error code went on.   This happened prior to installing my brand new equipment.  Will go out back and check 

[Jdk]

In the winter, when you run the heat, it doesn't turn on the AC compressor outside. If you are technical and want to bypass the nest like I did, you can turn off the power switch near the furnace, jumper your r and y1 wires together, then flip back on the furnace switch, this turns on the AC. When I did this, it caused a fuse on my furnace control board to burn out. The nest actually prevented this from happening so it did notice an over current on my y1 wire. I had to replace my fuse and fix my wire going outside and everything worked for me. I watched a lot of YouTube videos and spent 2 days on this. 

[JamesC1968]

I agree that the Nest E103 error usually means the $10 contactor and not the $200+ Nest has failed.  Also check the wires that go to the contactor in the outdoor unit for corrosion and loose and broken connectors, all of which can throw a E103 error.    

[Asma2019]

Well I had the same 103 problem , Before calling the tech to fix it , I just removed the front panel of the thermostat, pressed the y link , put the front panel iback , it is working fine so far about 15 minutes , if it gives a problem will update , 

[Nataliarisdana]

Where is the Y link? Do you mean where the wire goes? Thank you 

[Marie36]

The Nest thermostat has been installed and working for years working in both climate. I had a new HVAC system install in April 2022 thermostat  did throw an error but the HVAC guy resolved the issue.  
The thermostat was fine until we had a hot day and I put the A/C on. Y error.  It’s a Nest issue.  I bought a new Honeywell thermostat powered off electric put the new one in works fine.  

[SeeJayBee]

Thanks!  Just spent 3 hours troubleshooting this with electrician father in law and hvac tech friend on the phone and it turned out to be the contactor on the ac unit outside.  Easy job and $20 part.  

[H8_Nest]

Of course it will be tested, but my bet (clearly) is that it is doing exactly what the last Nest unit did before it died - throwing a phantom code that can never be fixed.

If there is a problem with anything but the Nest unit, I will post a follow up.

I did manage to fiddle with it enough to get it to cool the house down below 83 and sticky, but I'm guessing it is taxing the AC with more starts and stops than would be normal.

[Patrick_Caezza]

The Nest will fail in time if the contactor is falling. The contactor uses too much current and after some time the Nest thermostat's internal fuse fails.

[Sheri1]

Hi Patrick,

What is the contactor?  Is this a part in the Nest or the AC unit?  Is this something a HVAC person can fix?

Thank you,

Sheri

[JamesC1968]

The contactor is a $10 part that resides in the outdoor unit, along w/ the capacitor.  The capacitor operates on a magnetic switch, which pulls in when there is a call from the thermostat for A/C.   I replaced my contactor after my Nest threw a E103 error.   While not always, the E103 error usually means the $10 contactor and not the $200+ Nest has failed.  Also check the wires that go to the contactor in the outdoor unit for corrosion and loose and broken connectors, all of which can throw a E103 error.    

[Sheri1]

You are correct.  See my response to you above.

[Sheri1]

Not the Nest, it was the connector in the AC Unit as stated by Patrick_Caezza (below).

[H8_Nest · Accepted solution]

Brought out our HVAC company, and though it took two tries, they determined the Nest Thermostat unit had gone bad again. They replaced it with a non-smart Digital Thermostat at no additional cost. Just the service fees.

Glad to be out of the Nest business.

[Sheri1]

See my response to Patrick_Caezza above. It is the connector in the AC unit causing the Nest internal fuse to fail.  Once the AC guy replaced the connector (and two other issues) the Next was fine.

[michaelmior]

Do you mean the contactor? In my case, I tested the contactor and it seems to be working fine.

[Jdk]

For future reference, I initially tried replacing my contactor, I still had the issue. I figured I had a non obvious short in my 24v wire from my furnace control board to my AC compressor. I replaced my wire, luckily it was only a fifteen foot run. I'm back up and running. 

[Sheri1]

Not the Nest, it is the connector like Patrick_Caezza (below) stated.  I found out the expensive way.  I wish it was just the cost of the Nest.  Once the components were fixed the Nest was fine.  

[Mistic67]

I started experiencing the e103 code this season.  Last season was perfectly fine.  I decided to take a look into this e103 error, which is supposedly an overcurrent condition.  I have my 24 VAC, jumpered an ampmeter between the power & Y1.  I'm not sure what the surge was, but I can tell you my readings averaged 300-310 mA.  I haven't measured the coil resistance, but if you do the math, I have 77-78 Ohms of impedance.

So, my question here is, at what mA reading does Nest consider an overcurrent condition?  What is the rating of the Nest internal fuse?  In my opinion, 300 mA should be perfectly fine.

Nest 3rd Gen Learning Thermostat T3018US

[marksastre]

#following.

My NEST just spit out the E103 code.  No wires are broken or loose, nothing has been changed or moved.  Everything was working fine until it going out overnight last night.  My AC unit is a brand new Lennox purchased and installed one year ago. Are these NESTs really junk?  This is the third time i've gotten error codes over the last year.

[H8_Nest]

Switched off to a non-smart thermo and haven't had a problem since.

I'm wondering if there are just some systems (likely older ones) that don't support Nest well - almost like a personality thing.

[Mistic67]

Worth the spare wires,  I was able to add the common. That took care of the Nest getting power. The unit was short cycling. It turned out there was a wiring issue in the basement. After 3 junior techs,  they finally sent a master,  and he was the one that fixed it. Works perfectly now. 

But, I do know someone with a multi zone system. He also suffered the e103 issues. He replaced all Nests with some HP thermostats, and hasn't had a problem since. 

[marksastre]

My AC guys just left here - repaired the unit.  They 'think' the 24v wire may have been damaged somewhere.  They swapped wires and everything is working.  He didn't think it was the contacter, but we'll keep an eye on it. 

[MargH]

We had a new furnace, AC and Nest Thermostat installed in '21, and have had no issues with the Thermostat!!

[Markjosephp]

Hello MargH,

Thanks for reaching out to the Google Nest Community Forum. I'd love to know more about this.

Could you provide more details about how the installation went? Are you getting any power reports and need any help with your Nest Thermostat? Also, could you provide a rundown of all the steps you've tried?

I'll look forward to your response.

Regards,
Mark

[MargH]

Hi Mark,

We haven't  had any problems with our Nest Thermostat that was installed in 2021 with a new furnace, AC and the Nest Thermostat.  I'm  not sure I can provide any additional information!  It's  still functioning as expected!

[zoeuvre]

Hi there, 

Awesome! It's great to hear that your Nest Thermostat is working fine. As there's nothing to be resolved here, I'll be locking this thread for 24 hours. If by chance that you have questions or concerns in the future, don't hesitate to give us a shout or feel free to create a new thread.

I appreciate your assistance here, Mark.

All the best,

Zoe

[kpentecost11]

Our A/C unit is over 20 years old, we just got the E103 error but nothing has changed. Before I call warranty on the a/c unit itself, is it possible they will just want to replace the Nest and not the whole unit?

[JoeBland]

Everyone keeps saying the e103 code is the contactor !  I call BS. It’s a blown ic in the base 

[JoeBland]

Now!  Where do I get a replacement or mine repaired without spending $200+ for a new thermostat or $100 for some used base on eBay?  

[michaelmior]

In my case (and presumably many others), it was indeed a bad contactor. But of course that's not necessarily the only problem that could cause this error.