Google Nest Community

Cheezer12

Yesterday I upgraded from 2nd gen Nest to 4th gen. Prior to upgrade the system worked fine.After upgrade when Nest calls for cooling, the compressor comes on for a few seconds and stops.My wiring is Y1, G, Rc, W1. Power status is "good". Vin=36.7V. L...

Cheezer12

@CoolingWizard I do understand your explanation and theory of operation however in practice my 4th Gen Nest will simply not work correctly without C wire. I went through the exercise of swapping my 2nd gen Nest with 4th Gen nest twice and with the sa...

Cheezer12

@CoolingWizard Thank you for your reply. The transformer output is 27.2V so within the range that you specified and it worked just fine for last 7 years with Nest 2nd gen. So why doesn't it work with 4th gen? When I put back the 2nd gen everything wo...

Cheezer12

To add to my explanation I think the contactor switch coil is unable to keep the 240V compressor circuit closed due to significant voltage drop (down to 14V to 16V for a second) in the 24V control circuit. Once the compressor shuts off, Nest starts t...

Cheezer12

oops, autocorrect got me. it was supposed to say"AC compressor contactor switch". not contractor.To add to my explanation I think the contactor switch coil is unable to keep the 240V circuit closed due to significant voltage drop (down to 14V to 16V ...

Cheezer12

I was impatient and decided to hook up the C wire.Yup, C wire was my issue. 2nd gen Nest worked fine without it but 4th gen seems to need it, Google should tell customer that there is a 99% chance they will need C wire hooked up.I put a multimeter me...

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Nest 4th gen compressor engages for only a few seconds and stops.

Re: Nest 4th gen compressor engages for only a few seconds and stops.

Re: Nest 4th gen compressor engages for only a few seconds and stops.

Re: Nest 4th gen compressor engages for only a few seconds and stops.

Re: Nest 4th gen AC shutting off after a few seconds

Re: Nest 4th gen compressor engages for only a few seconds and stops.