topic Re: Duel Fuel - Short Cycling AC in Nest Thermostats

Duel Fuel - Short Cycling AC

GHR3286 — Mon, 04 May 2026 20:42:43 GMT

Hello,

I installed the nest but the system is constantly short cycling. The AC runs for a few seconds, turns off, then starts up again. I called my AC company and they said the system is in good order and the thermostat is wired correctly. They believe the issue is with the thermostat itself (although they clearly do not like the Nest thermostat). I have AC and a duel fuel heat pump. I’ve tried to lengthen the minimum run time in the app but it did not solve the issue. There is not a vent blowing on the thermostat. Any thoughts or advice is appreciated.

Old thermostat wiring:
Blue wire - O terminal
Green wire - G Terminal
Yellow wire - Y Terminal
White wire - W terminal
Red wire - R terminal (hot wired to RC)

Current Nest Wiring:
Blue Wire - OB terminal
Green wire - C Terminal
Yellow Wire - Y1 terminal
White Wire - W1 terminal
Red Wire - Rc Terminal

Re: Duel Fuel - Short Cycling AC

CoolingWizard — Wed, 06 May 2026 11:52:20 GMT

@GHR3286 ,

What tests did the HVAC perform on your system?

Did they verify the call for cooling?

Does the call for cooling drop shortly after the cooling cycle starts?

Did they use jumpers to manually initiate cooling to verify the system operation?

The AC Cooling Wizard

Re: Duel Fuel - Short Cycling AC

jasonjames2 — Wed, 06 May 2026 23:49:06 GMT

That pattern usually points more to Nest control logic or configuration (especially dual fuel setup / heat pump balance settings) than wiring itself, so checking equipment type settings and short-cycle protection is key issues like this often get resolved once the system behavior is tuned properly, kind of like how consistency matters when tracking things like over time instead of single runs.