No

A lot of stores like Napa sell kits to re-charge the air conditioner. I have
done it in several cars, including 1996 Bonneville's.

Rember, if the Freon leaked out, probably air (and moisture) leaked
in!!!!  There is more to air conditionin than just an Auto Zone can of
Freon!!!   Just a thought!!

It was originally charged with R134A, so you can buy refrigerant for it
without being a licensed A/C tech.  You may need to do some real repairs
first, though.  Somebody already mentioned it may need to be evacuated.
When they get full of air, then you need that.  You didn't give us enough
information to guess that sort of thing.

The level of difficulty will be contingent on

1. Type of refrigerant.
2. how bad the leak is.

There are drop-in substitute refrigerants (?Freeze-12?) for R12. R134A
is available.  Depending on where the leak is and how bad it is will
dictate how to repair it.

1. Very slow leaks which take a couple years to affect performance
include compressor seals, line fittings etc... where the system still
has refrigerant but cooling is inadequate can be charged with a can of
the same refrigerant in the system, but you are only buying time.

2. Fast leaks which cause little or no cooling include ruptured hoses,
line fittings, cracks in condensor/evaporator, etc.. where the system
has lost nearly all its refrigerant require the system to be opened up
and repaired and then fully evacuated before recharging.

3. Compressor failures should get a complete system flush and rebuild
including a new dryer/dessicant.

Bear in mind that if the system has been at atmospheric pressure for
any length of time moisture gets into it.  Any moisture in the system
will reduce the effiency and ultimately corrode the system from the
inside out. (compressor failure) If this is your case then a complete
system flush and rebuild including a new dryer/dessicant and then
fully evacuated before recharging.

A fully evacuted system should be able to sit overnight and not lose
any vacumn.