evacuating and recharging

I'm a novice when it comes to car repair. I have a 93 olds 88 so I decided I'll try to do what repairs I can myself.
I'm trying to recharge the ac with freon. First I need to know how to evacuate the system. Is this something I can do myself? If so does anyone know what tools I'll need.

You could if you had a manifold guage set, but it would be illegal if you didn't recover the refrigerant - which involves an expensive machine. You should also use a vacuum pump to suck down the system before recharging. If your system is empty you should consider converting over to 134A. Why are you recharging? Is the AC blowing warm air, now?

About a month ago the ac clutch broke. I was told that I needed to have alot of stuff repaired. So they converted the systems and replaced the compressor, receiver dryer, orifice tube. I've taken the car back 3 times since because it keeps loosing freon. So this 4th time I took it to them I was told it was a pressure switch and they wanted to charge me for it. I don't want to pay them anymore money so I replaced the switch myself and now I'm trying to put freon in it but it's just not working.

Ok, do you have guages? Or just a hose to charge from the low side? Also, which switch? The low-pressure switch on the accumulator? I think some AC systems have the pressure switches on the compressor - let me know which. Sometimes you can get by recharging without putting the system in a vacuum first.

I have just the hose to hook up to the low side.
It's the low pressure switch.
I've tried to fill the car but the gauge on the hose that comes with the can keeps going to the red.

ok, I'm not really familiar with that kind of setup, but I imagine that its just a pressure guage for the hose/low side. maybe the schraeder valve is not actually getting open and the freon can not pass into the service port. another thought, maybe the people who put the conversion kit on put the service valves on backwards??

at any rate, you may need to jump the low-pressure switch to make the AC clutch come on, at least until you can build a little pressure into the system.