why archived log size is small but fast recovery area still has a lot free space
that issue was caused due to lack of space in FRA(Flashback recovery area) if configured or the archive log destination.

option 1.
Restore the archive log to an alternate location which has space

example:

RMAN&gt; run {
set ARCHIVELOG DESTINATION TO '&lt;new location with sufficient free space&gt;';
recover database until time "to_date('2013-12-25 09:00:00', 'YYYY-MM-DD HH24:MI:SS')";
}


option 2.
Set MAXSIZE limit 

example:

RMAN&gt; run {
recover database until time "to_date('2013-12-25 09:00:00', 'YYYY-MM-DD HH24:MI:SS')" delete archivelog maxsize 50 K ; }