No heat, mineral dept is staying cold. Found SSU box with switch turned off, turned on, tested furnace, it’s running fine. Changed filters on lobby and mineral dept furnaces. The thermostat for the unit is in the lobby, mineral dept is dependent on the temperature in the lobby for heating and cooling. Unit running fine, made sure all the other furnaces started while I was here. All started, would recommend a one time check up on the furnaces this year.