A/C short cycling issues

721 Views | 5 Replies | Last: 1 yr ago by htxag09
Zombie
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Here is my setup: 2400 sqft two story home with high ceilings in living room with balcony overlook in the game room upstairs

One 6 ton unit outside. Dual zones that uses a dampner. Controlled by two google nest thermostats. Main intake is upstairs in game room, secondary intake is downstairs. Change both filters regularly.

Lately, the upstairs will not cool properly all of the time. It will kick on the unit outside, inside blower comes on, but no air coming to the upstairs vents. It does this and the outside unit short cycles after about 90 seconds.

Downstairs runs and cools just fine.

It seems as though its just the dampner gets stuck, but the strange thing is, if I run the upstairs intake with no filter, it doesn't do this. But I can't do that for fear of damaging the system. Could it be the filter is causing its just enough loss of enough air to full open the dampner? And if so, other than running it without the filter, what can I do? If I leave it off for about an hour, it seems to help as well.
htxag09
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AG
How long have you had the nest thermostats? Variable speed ac?

Could it be an issue with the nest thermostats? I know they work with zones, but don't think they work if your dual zone setup requires a thermostat damper control. Also "work" with variable speed but you lose the variable speed functionality.

I believe for more advanced systems, 3rd party thermostats aren't usually the way to go. We got a new variable speed trane unit a couple years ago and were told we had to use the manufacturers thermostat.
Zombie
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Honestly, I am not sure. Everything was already installed when we bought the house a couple of years ago. I know it's less efficient, but I wouldn't even mind if the whole thing was much more analog and just one zone. Any idea how to get Nest to just act as is if its all a single zone?
PeekingDuck
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AG
The Nests are likely your problem.
UmustBKidding
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Nest does support multi zone, and did not see the op say anything about multi speed. Multi would likely require reporting thermostat not nest. And removing filter corrected issue points to a static pressure/damper issue. There are some reports of insufficient current capability in some multi zone controllers that require you to supply power to them via the c lead.
I would measure the actuator voltage to verify presence and level is sufficient.
htxag09
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AG
UmustBKidding said:

Nest does support multi zone, and did not see the op say anything about multi speed. Multi would likely require reporting thermostat not nest. And removing filter corrected issue points to a static pressure/damper issue. There are some reports of insufficient current capability in some multi zone controllers that require you to supply power to them via the c lead.
I would measure the actuator voltage to verify presence and level is sufficient.
Nest does support multizone, but not multi zone with adjustable dampers. At least I don't think they do.

And correct, the OP never mentioned multispeed. But the reason I asked is it's kind of silly and not worth it to have multiple zones if you have single speed. At least not in my unexpert opinion.
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