Both units are frozen and need service found one damper unplugged and two clogged filters second floor thermostst is a byrant evolution controller, first floor thermostat and basement thermostst may not be compatible as well due to sensor wiring confirmed furnace has a 75va transformer to power the zoning board so power should not be of concern for the nest batteries. Reccomend customer sign up for a maintenance contract customer agreed rescheduled to allow both systems to thaw collected for ma contract. Returned 7/31/20 installed 2 nest thermostats removed clogged filters confirmed units were thawed performed clean and check on two ac systems tested and inspected all electrical components and controls confirmed proper operation of the damper system check charge on both ac units cleaned coils all operations are normal at this time.