Solution to Nest causing reverse valve to click on heat pump?

[Anonymous]

Has there been a solution to this established problem with the Nest Learning Thermostat causing the reverse valve to click?

https://www.googlenestcommunity.com/t5/Nest-Thermostats/Learning-Thermostat-making-clicking-noise-ou...

https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-Learning-Thermostat-Causes-Clicking-Noi...

https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-causing-heat-pump-reversing-valve-to-cl...

https://www.googlenestcommunity.com/t5/Nest-Thermostats/Nest-Thermostats-Clicking-noise/m-p/256096

I just got a new (and uncomplicated) heat pump and air handler system installed with new thermostat wiring so I now have a C wire.  My HVAC guys installed my Nest thermostat but immediately heard clicking sounds from the reverse valve.  They also determined that the issue is due to the Nest as it stops immediately when the front part of the Nest is taken off the wall.  

From what they read, they thought it might be caused by a low battery level in the nest that was causing the voltage changes to the reverse valve, so they showed me how to temporarily override this on the wiring of the actual HVAC system until the issue with the Nest is resolved (it is temporary because it causes the system to be unable to switch to heat).  I charged the nest and also left it hooked up overnight, but the problem still occurs when I checked it this morning by undoing the override.  

I read all the related posts and none had posted a solution.  I will buy a different brand thermostat instead of paying to have a Nest Pro to come out.  This is an established problem caused by the Nest, and either there is documentation for how to fix this that I can do myself, or my Nest is defective and should be replaced.  I am open to either option.  Thank you.

[CoolingWizard]

Did your technicians measure the voltage  and current arriving at the reversing valve coil? I have only seen this problem when there is insufficient current being supplied, either from the transformer through the thermostat and back to the reversing valve. The thermostat wire should the solid conductor 18:gage unless the total cable run is longer than 150 feet. 
if this was an actual problem with the nest thermostat or the back plate, there would be a lot more customers it would be complaining about this because there are literally hundreds of thousands if not millions of heat pumps in service in the country. The cases you cited are all back from 2022 and one from 2021..

The AC Cooling Wizard

[Anonymous]

The wire from the air handler to the thermastat is 18/7 solid copper.  I don't know about the wiring to the heat pump, but it's the same as my last heat pump which worked fine with a battery thermostat.

I believe they did check the voltage and current, and since the clicking stopped when the nest was removed, they identified it as the cause of the problem. 

[Anonymous]

So if I put a different thermostat on and I have no clicking sound, does that indicate it's the Nest causing this issue?

Why does it matter what year the other posts are from?  I don't believe this is an issue for every Nest, but it is an issue that happens to some.  My question is how do I fix it?

[Markjosephp]

Hello folks,

I know it has been a while, but I wanted to ensure that everything was covered here. 
 

Thanks for lending a hand, @CoolingWizard.

@Anonymous, we'd like to take a look at this for you. Could you please fill out this form with the needed information? A member of our support team will be in touch over email to help.

Regards,

Mark

[Anonymous]

Completed.

[Markjosephp]

Hi beckybell2355,

Thanks for completing the form; we have received it. Soon, a member of our upper team will contact you via email. So please continue the conversation there, as this thread will be locked within 24 hours.

Regards,

Mark

[CoolingWizard]

The nest uses a much more sophisticated digital control system inside of it opposed to one of those simple touch contacts. The clicking sound you heard was that the Nest was trying to close a relay inside of it to allow the power to flow from the R wire to the Y wire and there was not enough current arriving to allow that to happen or there’s a intermittent short on the cable causing a loss of power. 

A smart thermostat draws power as well although it is only a few hundred milliamps. To help identify this a thorough testing needed of the Nest Thermostat.  Need measure Voltage arriving, and the current. Then the Voltage and current leaving the thermostat. Only in that way can a power loss be properly identified.  

AC Cooling Wizard

[Anonymous]

The Nest unit itself was not making a clicking sound.  It was the reverse valve of the hvac system.

The Nest battery power was increasing while attached to wall, but to ensure that power wasn't an issue, I took it off and charged it as well.  There was sufficient power.  And my Honeywell smart thermostat that requires a c wire that I replaced my Nest with is working just fine and there's no clicking sound from the reverse valve.

[Jenelyn_O]

Hi there,

I'm sorry for the delay. I checked your case and one of our support sent you an email. Please check your inbox and continue the conversation there. Otherwise, I'll be locking this thread after 24 hours. 

I appreciate your help, @CoolingWizard and Mark.

Best,

Jenelyn