If you know, for sure, you have an AC leak repair it as soon as possible. The car will be drivable but, do not use the AC. Most people, including me, like to use the AC until it does not work any more. BIG MISTAKE! Not only you will have to change you evaporator but, your compressor as well. On the other hand, you may want to considering converting to r-134 and check all the rest of components at the same time i.e. vacuum actuators, since the dash has to come out. Do a search on the subject on the upper right corner on AC related items.
Sorry about the bad news! Believe me, I know the feeling.
P.S. Unfortunately, if you are low on freon, your auxiliary fan will not work until it hits 115 degrees?. Check your aux. fan and engine temperature, specially at idle.
[This message has been edited by J.HIDALGO (edited 10-12-2000).]