Nest learning gen 3, AC fan speed ramps up and down

[pkgannon]

I recently installed a Nest Learning thermostat,  gen 3. I have separate heating and central cooling. During cooling, the fan initially spins up to high speed, stays there for about 30 seconds,  then spins down to a very low speed. It stays at low speed for about 5-7 minutes (sometimeslonger),  then spins back up to high. Once back at high speed, it stays for a while (haven't timed it) before it spins back down and the cycle starts again. 

My wiring configuration is as follows. 

 Cooling g: Y1, G, Rc

Heating:W1, Rh

Auto schedule is turned off. I do not have any power issues or error codes displayed. Fan schedule is not enabled. 

The fan speed issue is making it take much longer to actually cool the room. 

I would appreciate any advice on how to resolve the fan issue. 

Thanks

[Jenelyn_O]

Hi pkgannon,

Thanks for reaching out. I'm sorry for the delay. I appreciate the information you've provided. I'd like to take a closer look at it. Could you please provide your Nest Thermostat power readout? 

You can follow this guide:

1. Go to your thermostat Quick View menu.
2. Go to Settings.
3. Look for Technical Info.
4. Select Power.

Also, please check your thermostat Energy History. It might help you see what your thermostat was doing previously. You can visit this support article on how to check Energy History in the thermostat or in the Nest app.

Best,

Jenelyn

[Jenelyn_O]

Hi there,

It's me again! I just want to check if you managed to see the response above. Please share with us the needed information, as it will help us to move forward.

Thanks,

Jenelyn

[pkgannon]

Hi, sorry, I didn't see the original reply. Here are my power readings. 

Battery 3.856v

Voc 36.66v

Vin 35.68v

Lin 40mA(i)

[Jenelyn_O]

Hey pkgannon,

Thanks for providing your Nest Thermostat power readout. Your thermostat power reading is totally fine. Could you please try to manually change your thermostat fan speed and monitor if the issue persists? 

You can follow this guide:

1. Select Settings .
2. Select Fan.
3. Choose System fan speed.
4. Select the fan speed you'd like to use when your system is heating or cooling your home. Depending on your system you may see Low, Medium, High or Auto, if you have a multi-speed fan.
5. Choose Done to set your system's fan speed.

Also, you can visit this support article for more information.

Best,

Jenelyn

[pkgannon]

Hi. I checked my settings and I don't have the option of setting the fan speed. It only offers to set a schedule. I believe my system does have a variable speed fan, but it's possible it's not compatible with the Nest thermostat 

[Jenelyn_O]

Hi pkgannon,

Got it. Thanks for keeping me in the loop. Variable speed fans are compatible with Nest thermostats, but the fans will only operate at a single speed.

Please provide the make and model of your system. It will help us to further check your fan compatibility with Nest thermostats. 

Kind regards,

Jenelyn