Neat thermostat Fan always running

[JtotheMe]

 

We’ve had the nest a few years and recently I’ve realized that the fan is always running.

Yes fan is off on nest. 

Yes fan runs when temp is below or above what it should be.

yes fan runs when faceplate is off.

Found a thread from last year on here where someone had an hvac specialist come out & they stated they replaced the control panel to resolve. Just looking to get some insight as to what is actually being replaced (is it the panel with the wiring I’ve posted or something more in depth)

Photo of the wires behind the nest…. & yes fans still running lol 

[sporfrog]

If the fan on the HVAC equipment is running when the Nest thermostat is removed from the base, it is probably an HVAC system problem rather than a thermostat problem. In that case, as you suggested, it might be a control board on the HVAC system (rather than the thermostat). Or maybe there is a jumper or switch on the HVAC system set to intentionally run the fan always? You could remove the wires from the thermostat base just to be sure.  Maybe check to see if any (especially green) have the colored insulation removed in an unexpected place, or if there is anything metal unexpected under the plate.

You might also just try cutting the power to the HVAC system to reset it. Turn of the circuit breaker or if it has a switch at the unit flip it off for a minute or so then back on. Rarely makes a difference, but it might.  Think of it as a reboot on a computer.