Nest Thermostat short cycling air conditioner

[schreckpc]

Hello!   I installed my Nest a few months ago in my 26th floor condo apartment in South Florida with water-cooled air conditioning unit.  The apartment is 1100 sqft and has many windows with direct sunlight in late afternoon.  I only have two Routines:  Sleep and Home.  Sleep is 72 from 10pm to 6am and Home is 74 from 6am to 10pm; we also have an Eco routine for when we depart the premises.   When I review the History of the unit's operation, it is consistently -- day and night/early morning -- cycling on for 5 minutes, then cycling off for about 10-11 minutes.  The ON cycle is pretty consistently 5 or 6 minutes, while the OFF period varies a little more, from as little as 6 minutes in heat of the day to as long as 11 minutes.   This creates around 4-5 ON cycles per hour, every hour.  Is this normal?  Is there a setting I need to change?   It seems the unit kicks ON when the temp drops one degree from the temperature setting.   

Temperature Preferences:

Early-On:  ON, Ready
Airwave:  ON, Ready
Time-to-Temp:  Ready
Leaf:  Ready

[Patrick_Caezza]

@schreckpc 

Which Nest thermostat do you have?

How is the base wired?

[schreckpc]

Hi Patrick.  I have the regular Nest Thermostat not the Learning one. It was $99 from Amazon.  The wiring was pretty straightforward, right by the instructions.  I have 5 wires: Y, G, R, OB, and the C.

[Patrick_Caezza]

The symptoms that you mentioned are classic of not having a C wire. Double-check to ensure it is fully inserted into the terminal and that the bare copper wire is straight and shiny.

If that doesn't help, try resetting factory defaults and setting it up again. Sometimes they can get a programming hiccup, and starting from scratch will solve the problem.

[schreckpc]

Thank you, sir.  I appreciate your suggestions, but let's talk through them, please.

C-wire anomaly.  If the C-wire was open/disconnected, wouldn't the Nest tell me so?  The model that I have requires the C-wire or an adapter, so I have a hard time believing there is a C-wire anomaly when the thermostat is working just fine...just too many cycles (perhaps, see below).

Factort Reset.  I have done this once since original setup.  I found the Nest had dropped offline and, while showing connected to my home's Wifi, it would not appear the Google Home app on my iPhone.  It also said there were low batteries, even tho I had just changed them.   I did this reset over a month ago and the system is working just fine now, again, except for the high cycle rate.

Additional comments.   There are a lot of blogs and customer complaints out there about this issue with the Nest.  A number of them have switched to the Ecobee...I am considering eating the $99 and doing the same.   As an engineer, I consider what the device was designed to do and how it was spec'd to operate.  From what I can find online, the deadband (AKA temp differential) is +/- 1.0 degrees F.  It seems highly likely/logical this sensor is doing exactly what it was designed to do: when the temp rises 1.0 degrees F (in my case, from 74 to 75 during the day), it calls the AC to cool, and it only takes 5 minutes to recover that one degree in my smallish space.   With all the windows in my apartment and direct sunlight at times, it takes about 10 minutes to lose that degree of cooling and go back to 75.  In other words, I don't see there is anything "wrong" with the Nest, but I do believe, perhaps (and as noted in several blogs out there) the Nest needs to enable a user-defined deadband because +/- 1.0 degree is too tight in some/many instances.  The Ecobee allows the user to configure this setting while the Google Nest does not.   

Again, I totally appreciate your suggestions, but I'm struggling to believe there is anything wrong with the C-wire or the Nest performance when many, many Nest users are encountering the same issues.   

[schreckpc]

@Patrick_CaezzaSee above reply, Patrick.

[zoeuvre]

Hi schreckpc, 

I wanted to stop by and see how I could help.

Have you checked your air filter if it is already dirty and needs to be changed? If it is, then replace your air filter. After that, observe if the same behavior persists and let me know how it goes.

Thanks for the help here, @Patrick_Caezza.

Best, 

Zoe

[zoeuvre]

Hi there,

I wanted to check and see if you managed to see the information I shared. Please let me know if you have any questions from here. I would be happy to assist and make sure you are good to go.
 

Thanks,

Zoe

[schreckpc]

@Patrick_Caezza  There has been no change in the behavior of the Nest.   I can also state that I had a unit checkup and the system is tip top.   The filter is clean and regularly replaced.  Filter has nothing to do with this cycling pattern.   I also called the Nest support line and the rep walked me through setup and Settings and all seems to functioning correctly.  

To the orignal issue, it still cyles for about 5-6 minutes ON, and then 8-12 min off.  This pattern repeats about 4-5 times per hour.   Upon install, I only used two temps:  Comfort (74) for the day since we work from home, and Sleep (72).   During the summer in FL when it's very hot outside, we get acclimatized to the heat and 74 starts to feel "cold" when indoors, so I added a third temp called Workday (76) that spans the 9am-5pm window while we are home working.    It made a big difference...with the temp set to 76, there are only 2-3 cycles per hour, but the ON duration is still only 5 minutes.   So, this is what I have learned over time:  

 -It's a known issue with the Nest the temp differential that triggers ON is only one degree, so the slightest variation in temp triggers the unit ON.  If the unit is efficient (and/or the space small), that one degree is recovered quickly and the unit toggles OFF.   This is a poor design that competitors have overcome.  Again, I believe the situation in my apartment makes the Nest a poor choice:  I have an efficient a/c unit, a smallish space, and lots of windows.   The temp fluctuates greatly about +/- 1 degree in my application.   You can read all about this gripe here:  https://www.googlenestcommunity.com/t5/Nest-Thermostats/Anybody-from-Nest-Please-make-the-temperatur...

-The Ecobee has a user-settable temp differential band that allows a wider variance in temp so the unit is not "chasing" this small one degree band.   I am going to give this another month of trial with the new Workday temp.  If nothing changes, I am switching to an Ecobee...and I'll have a slightly used, but totally functional Nest for sale, cheap.    

[kneedabike]

Hi schreckpc.  I just stumbled onto this (and others similar) thread and have a few ideas.  Is there any supply register blowing cold air in the direction of the 'stat?  If so, redirect the air away from it.  The theme of a lot of these concerns is that the unit is too "quick on the draw".  So let's try slowing down its reaction time by surrounding it with some mass.  You might try hanging a glass saucer over the face of the Nest or draping a towel over it as an experiment.  This would slow this trigger happy character down by slowing down the speed at which it gets triggered.  Please let me know if this affects the 'stat.  If the towel idea works, you could embroider something like "Nest Corrector" on it and make it a conversation piece.  

[Illusion000]

Same issue same findings, hope this get updated.

[dany2]

I am having the same issue. I went from a provider thermostat to Nest and it keeps short cycling. I don't have the c wire, so, I will update after installing the C wire power adapter. I have been looking for solutions but I haven't yet

[Coop1]

I'm curious if you were able to resolve your short cycling issue.  I too have a unit that is short cycling but in a much different way.  My unit is shutting off briefly when there is a change in the scheduled temperature that is lower than the current temp.  Ex: temp is set at 76 and the system is actively running to meet 76 but then the schedule changes the target to 74.  What happens is the system shuts down then about 30 sec later it restarts, which is very hard on compressors.  Unfortunately I learned of this behavior only 3 days before my compressor seized.  Needless to say I will be switching to Ecobee when my replacement system is installed.

[schreckpc]

Hello, team.   I have not resolved the issue...it continues to perform the same way.    More data, however.  I just returned from a two week trip where I set the Nest to my Eco mode which is 80 degrees -- recall that I live in South Florida, where it's VERY hot this time of year.   The Nest continued to cycle for no more than 5 minutes to keep the temp at 80.  The OFF intervals were longer due to the high temperature setting, but the system has the same tendency.  After observing for the full day home, it's cycling a bit longer now (5-11 minutes depending on time of day), but the overall behavior is the same.  The system chases a one degree differential.   Ecobee is the way to go @Coop1; I need to make the switch before the Nest kills my unit.   

[dany2]

Yes I was able to resolve my issue with the installation of the c wire adapter. Now it works great. 

[Sboyle2745]

I am experiencing the same super short cycling issue on my Nest Learning device.  I just installed it, over 2 weeks ago, and the short cycling continues. It didn’t do that with my old thermostat and the air conditioning unit is only 2 years old and well maintained. I’m considering the advice of others here, maybe Ecobee is the way to go!?  Google, help us out here please!

[kneedabike]

Hi Sboyle2745.  I am just now arriving at this thread and it seems I was too late with my ideas to help schreckpc.  Please have a look at my response to his/her comment on April 30 and consider my thoughts.  If you have a go at it please let me (everyone) know how it went.  Thanks and good luck!

[schreckpc]

ATTENTION:  The Nest has claimed its next victim.   

Yes, I waited too long and now my compressor has failed, necessitating full unit replacement.  With the Nest cycling my unit 5-6x per hour for 24 hours a day, the 100+ cycles per day took its toll in the six months since install.   I know I have no recourse but to share in a forum like this.   Buyers/users beware:  the Nest will wear out your air conditioner due to its oversensitive temp differential.   My kid sister had a similar experience a few months ago and her technician agreed the Nest is killing equipment.  She switched to Ecobee.   I will either go with an Ecobee or a Honeywell T9.   The Nest is a killer, and users should beware.  Just read this thread for my experience.  If your unit is NOT cycling at that rate, perhaps the Nest is for you.    It works in its intended manner, but that temp differential was TOO small in my application and I paid the price.    

[Sboyle2745]

Thank you, to our (former) community Nest engineer, schreckpc. I found your detailed experience very helpful and took your advice. I turned off my new Nest and am buying an Ecobee now. My  Nest literally cycles on/off every other minute when attempting to reach a lower temperature (no matter if it’s one or five degrees lower). I want to avoid buying a brand new compressor due to poor Nest programming and will certainly share this negative experience with others.  Thanks for posting your experience. 

[kneedabike]

Hi schreckpc.  So sorry to hear of this...  I didn't see this  most recent post before responding to a comment of yours from April 30.  Wish I had visited this thread then.  But I've learned a lot about smart thermostats.  Our utility is offering upgrades to either Nest or Ecobee.  I will be choosing not Nest. 

[Googledad]

Same issues here - constant cycling of the AC when trying to reach a lower temperature. Concerned of the wear on compressor. Class action lawsuit for air conditioner compressors damaged by Nest thermostats? Hopefully Nest addresses this with a fix before it comes to that 

[Zachrivenburgh]

Same issue. Brand new nest thermostat, I have a C wire, it’s straight and clean. Short cycles every few seconds.

[schreckpc]

The Plot continues...

Unresponsive and unattentive warranty service.  I have made two Warranty Claim inquiries on my Nest that is still under warranty,  The website gives the laughable "Your email has been sent.  Thanks for providing your information. We'll reach out to you soon."  Well, Google, if by "soon" you mean like not in this lifetime, then yes, Soon.  I have tried both Chat and Call options to no avail.   If you purchase a Nest, you are stuck with it.