Nest learning thermostat 3rd generation running latest firmware 6.2-27. Five wires Rc-W1-Y-G-C coming from a trane forced air gas furnace. Problem: Fan only mode do not function. Tried to enable the fan from Nest, Google home app when the thermostat is not in an off setting.
Originally installed by a Google recommended pro, and verified fan only mode worked.
Tried with support provided replaced thermostats, and works first time. Stops working after a software upgrade, which happens automatically.
Help appreciated.
Thanks.
