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A/C cycles on and off

lfpd42
Community Member

My A/C just cycles on and off continuously.  I moved the location of the thermostat, but it has always worked in the past.  I only have three wires;  Red, Yellow and Blue and the system is only for A/C.  I have had the thermostat wired up and on the base overnight, but it still says low battery.  The thermostat was completely dead when I hooked it up.  Can it be a battery issue.  I have it plugged into the wall now and I am going to reconnect tonight.  Can it be anything else?

1 Recommended Answer

lfpd42
Community Member

It turns out I only needed two wires for my system, the red and yellow.  Since doing that everything is working fine.  Thanks for the help!

View Recommended Answer in original post

16 REPLIES 16

mikev552
Community Member

Are you using the C slot on the Nest? This is what gives constant power to the thermostat and hopefully solve the issue.

The blue wire might be the C wire. Red is power and Yellow is the AC switch. It's best if you post pics of the thermostat wiring and the same wires going to the control board near the AC blower motor. 

lfpd42
Community Member

Yes, I am using the C wire.  I have a red wire hooked up to R, a Yellow wire hooked up to Y,  a Green wire hooked up to C and a white wire to W.  THis is AC only, so I don't know if the white wire means anything. I have a blue wire that should be the common, but at the air handler the blue wire is wired to the green wire,

mikev552
Community Member

Its best if you could post a pic of all the wiring at both ends to see what is going on here. Sounds like something might be wired incorrectly..

lfpd42
Community Member

67511257888__FE0D10DF-C654-415B-9570-D1F5C2CB0B4C.jpg

lfpd42
Community Member

Here is the wiring at the Air Handler

mikev552
Community Member

wow, you have a lot of wiring going on there for just AC. You still need to verify what colors are attached to the control board and follow the wires to the thermostat making sure they match. All those split wires is not ideal. You might even consider a complete rewire. 

lfpd42
Community Member

The white cable on the right is going to the thermostat.  You can see a yellow, green and red wire coming out of it

lfpd42
Community Member

Thanks.  This has always worked in the past as is.  I just moved the thermostat from the first floor to the second.  Would  low battery on the thermostat cause the a/c to cycle on and off?

mikev552
Community Member

Yes, if the nest is not getting power it will work intermittently. All I would suggest is check the wire your using as the C and check the connection at both ends.... something could have moved since u did move the thermostat 

mikev552
Community Member

IMG-20220522-WA0016.jpeg

mikev552
Community Member

Can you take a pic of the Nest screen showing the connected wires? In your case, you should have Y C R G connected if its just AC. W is heat

Patrick_Caezza
Diamond Product Expert
Diamond Product Expert

Who is the manufacture and what is the model number of your air handler?

You probably need to install a C wire. One of the symptoms of needing a C wire is the A/C turning on and off.

If the Google Nest THermostat was completely dead, then you will need to replace the AAA batteries with a new set of Alkaline batteries. Do not use Lithium or other rechargeable type batieries.


To ensure that I see your reply, please tag me using @Patrick_Caezza

MelbaDT
Community Specialist
Community Specialist

Hey folks, 

 

Thanks for responding, Patrick_Caezza and mikev552. 

 

lfpd42, chiming in to ensure everything is covered here. Have you seen the latest responses above? If yes, have you had the chance to try the suggestions as well as get the necessary information being requested?

 

Best, 

Melba

lfpd42
Community Member

It turns out I only needed two wires for my system, the red and yellow.  Since doing that everything is working fine.  Thanks for the help!

MelbaDT
Community Specialist
Community Specialist

Hey there, 

 

You're welcome and that's awesome! Glad to hear you've sorted it out. Let us know if you have further questions about this. 

 

Best, 

Melba

MelbaDT
Community Specialist
Community Specialist

Hi, 

 

We haven't heard from you in a while so we'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the Community.

 

Best, 

Melba