Sounds like it has heat strips or heat pump. If a heat pump the temp. is controlled by outside ambient air. If it has heat strips maybe on is broken, From your location in Louisiana a heat pump should work fine but IMO the temp. is too low. Although it is currently cool in your area IMO again the A/C should also be colder. If it is a heat pump/AC combo. I would have it checked by a professional and make sure the inside and outside coils are clean, Since you do not own it and am checking it out I would insist the the owner replace the unit. Good luck and keep us posted.
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