blower fan turns off when Nest is engaged in cooling

[ike41]

Replaced old thermostat with Nest gen 3. My wires are red (1), green (1), white (1), yellow(1). The old thermostat had a connecter between the Rh and Rc, the previous thermostat connection was Red to Rh. With Nest, I connected the Red wire to Rh, Yellow to Y1, White to W1, Green to G. Heating works fine, when I changed to cooling the a/c would turn on along with the blower fan in furnace, within 2 minutes the blower fan in furnace shuts off with the a/c unit still running. I tried to remedy this by switching the Red from Rh to Rc connection. Same result. I tried different modes in Nest (cooling only, heating and cooling), same result. I reinstalled the old thermostat and the cooling runs fine without the blower fan turning off.

Any remedy for this or others experiencing same issue? 

[Ryan_G]

Hi ike41,

Thanks for reaching out here in the community and we're sorry for the delay.

I'd like to jump in here and check a couple of things for us to further isolate the issue. First, we'll need to check if we've selected the right equipment from the settings > equipment > select the right source of heat and equipment type. Try to restart your Nest thermostat once done.

Let me know how it goes by replying to this thread.

Best regards,

Ryan

[Ryan_G]

Hey ike41,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Best regards,

Ryan

[Ryan_G]

Hey there,

Thanks for being here in the Google Nest Community. 

I'd like to bump in here and make sure that you’ve seen our response.

Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Have a great day.

Best regards,

Ryan

[pablomc]

I have exact same problem. Outside unit stays on and fan turns off and on intermittently. Wiring is exactly as yours and the only remedy so far is to remove Nest and use old thermostat. 

[Coral_787]

I'm having the same problem...kinda. I have a Carrier FB4CNF with heat pump and 2 Nest thermostats that are installed correctly and have been working fine. When I turn the temp down, compressor kicks on and thermostat shows cooling, but blower won’t kick on (even after delay). And when it finally does, it’s very intermittent/erratic, running for 2-3 min or 45 min or not at all. Status lights on the control board indicate everything is operating normally. Had a tech come out and he wants to replace control board for $800.. I just think there's something else going on.  Any thoughts out there? I have someone else coming to look at it tomorrow.

[adamski]

I am having similar issues. The Nest will trigger cooling (condenser coils will cool and blower will start), but the blower only runs intermittently. I can trigger the blower by running a fan test, but it won't start when I manually try to start the fan, nor will it run according to a fan schedule. Similarly to @Coral_787 HVAC person was called and they have since replaced the board. The combination of blower fan working intermittently + blower works when tested using Nest + doesn't work when manually started via Nest = potentially a Nest issue. If it was a problem with the blower, system control board or elsewhere on the system, I wouldn't expect it to work at all.

[Coral_787]

So I had a 2nd tech come out. He was very knowledgeable and said the system was operating normally (of course) and was not the control board. He recommended swapping out the two Nest with original Honeywell basic thermostats and see if the issue continues before dropping $$$$ on anything.  He's seen first and second generation Nest have this type of issue 3-4 yrs in. I'll keep you posted @adamski after I swap them out.  I also  have the same issue with fan not operating as per schedule like it used to. 

[Ryan_G]

Hey everyone,

Thanks for all the update you've posted here in the Google Nest Community.

I'd like to further check if we've already select the right equipment type in the settings > equipment > heat type and source. Sometimes, we tend to overlook these settings and as a result, we may experience some strange behavior on the unit.

Let us know how it goes by replying to this thread.

Regards,

Ryan

[Ryan_G]

Hey folks,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Best regards,

Ryan

[pablomc]

I connected the "C" terminal from system board to Nest thermostat and everything is operating normally.  Thank you.

[Ryan_G]

Hey pablomc,

Thanks for the reply and for bringing the good news.

It's great to hear that your system is up and running now. Let us know how it goes in the next couple of days by replying to this thread.

Regards,

Ryan

[Ryan_G]

Hey folks,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Best regards,

Ryan

[Jake]

Hey all,

I wanted to check in, and ensure everything is working properly. Please let me know if you are still having trouble, as I will be locking the thread in 24 hours.

Best regards,

Jake

[pablomc]

Hello,

Checking in to confirm problem solved and no current issues with Nest thermostat.

thanks

[Jake]

Hey pablomc,

I am glad to hear you were able to get the issue resolved. With that being the case, I am going to lock the thread at this time. If you have any questions from here, please feel free to create a new post.

Best regards,

Jake