Ac stalling with newly installed Nest termostat.

[Xellos2099]

Long story short, around a month about my townhouse we changed out the condenser and installed nest as thermostat and it was good. It took longer to cool the house but ti work. A few days ago, we noticed temperature is hotter than usual. We set the ac to 72 degree but it was closer to 76. Today I decide to have a good look, while nest say it is cooling the condensor was not running. To be more precise, when I check earlier, it run for a few minute and then turn itself off. It is like the ac is stalling. I am not sure if it is the condensor issue or it is the nest. since we change both it is hard to know but it seems the nest ac stalling is not all that uncommon

 

[boomerang]

Situations like these are why I always keep the old thermostat around for awhile after replacing it.

 

[ch33zw1z]

Verify your Configuration on nest website, open a ticket with them, in the mean time Google your problem and see how others fixed it

 

[NutBucket]

Perhaps its some odd coincidence and there's some other issue with your HVAC system preventing it from operating normally (low freon, perhaps?)

 

[Zorba]

Kind of sounds like an overheat switch or liquid carry over switch opening.

If you are good with a multimeter, you can check for voltage on the single wire from the furnace going into the condenser. If it is being told to run, you should have voltage (24 Vdc, IIRC). If you have voltage on the control wire, then the problem is at the condenser, if you don't the problem is in the thermostat or furnace.

 

[Red Squirrel]

I would check for 24vac at the compressor for the relay just to rule out the thermostat. If you get 24v then it's probably a coincidence and it's another issue. If you get a lower oddball voltage, I'm almost wondering if somehow the nest is loading the transformer hard due to an odd fault and the relay is not getting quite enough voltage to stay on.

 

[piasabird]

I have a fairly new furnace/air conditioner. The unit has a circuit board in it that has something called a limit switch. If I used an air filter like one designed to take out more dust or a HEPA filter, what would happen is the air limit switch would shut off the furnace. So I went back to the old ratty green filters. The better air filter actually slowed down the furnace airflow below acceptable limits. This makes the air limit switch go off and shut off my furnace. Try an air filter with better air flow.

 

[NutBucket]

This is good advice for any hvac system. Use a super shitty filter. The "good" filter will decrease airflow to the point it effects efficiency. Bad idea.

 

[gorcorps]

This is good advice for any hvac system. Use a super shitty filter. The "good" filter will decrease airflow to the point it effects efficiency. Bad idea.

True story. This craze of putting allergen filters in your HVAC system has caused people problems they don't even realize right away. Basic filters go in your HVAC system, and if you need separate air purification you can buy purifiers designed for that purpose.