Greetings , i moved to a rental townhouse in south floroda recently . the townhouse has 3 levels. i noticed that the rooms on the third floor are much warmer than the 2nd level . the AC ynit is installed in the second level . when Ininspected the AC ubit , it looks like the reuten ducts are not connected back to the unit . is what i am seeing actually a return duct and should it be connected to the main unit ? could thos be contribyting to the warmer topms on the third floor ?