Your bottom freezer model might be from 1964 per the library (see "Manuals & Literature" link at top of page).  The closest model number to the one you provided is covered by the Frigidaire service manual for 1964 units.

Models like yours have a fan base here and more than a few members own one.  Some have had cooling issues caused by one component or another.  Your defrost heater may have stopped working, as that problem has been addressed here more than once.  There's a resistor or some such component that can fail.  If your freezer is icing up, it could be inhibiting the flow of cold air into the fresh food section, either by stopping the fan or by constricting the flow of air it generates.