If you don't have working ac, try this first:
-buy some R134a (you need about 28oz to completely fill the system, or about 2 and 1/3 of a typical 12 oz can). Do not use other refrigerants on your 100 series unless it specifically calls for it (mine has a sticker under the hood that says "R134a use only").
-buy, rent or borrow a vacuum pump and pressure gauges
-run the pump on the low and high pressure side to evacuate the system
-test the vacuum by leaving the gauges on for an hour: If it maintains the same negative pressure on the system, you probably do not have a leak. If it drops down to ambient pressure, you almost certainly do have a leak
-If you don't have a leak, refill with new R134a in the low pressure port only
-If you do have a leak, time to investigate where: buy a R134a dye kit and a black-light flashlight
-Run the R134a dye kit through the low pressure port while running the A/C at full blast
-In a dark garage, investigate all piping and components of the system with your black-light flashlight. This will help you isolate any leaks that you might have. Check the obvious spots first: under the A/C piping near the passenger side wheel well, all the way back to above the spare tire in the rear, check both "H" & "L" ports for potential leaks, check the compressor, and check the condenser. If you still don't see anything remove the glovebox and the evaporator core cover and look for dye leaks in there. Also, if you feel like ripping apart the rear interior panel to check the rear evaporator core, it could be a culprit. Hopefully you will find your leak. Now fix it.
-if one of your lines has a leak, you can replace the component ($$$ and a pain in the *ss) or try to fix it. I've had success with Dorman 5/16" line repair kits, but there are many different sizes that are available.
-if your compressor is leaking, you will probably need to replace it. You may also have to refill the oil with ND oil #8 in this case (sorry, I don't know the oil capacity).
-once you have solved your leak problem, re-run the vacuum for an hour or more to evacuate the system of any air and moisture
-then refill ~28oz of refrigerant through the low pressure port. The cans can take quite a while to fill the system, since the compressor needs to kick in to pull in more refrigerant.
-enjoy
There are many components to the AC system, so you might be stuck in a trial and error game here.