I have a 2005 Nissan Sentra, going on my 3rd summer with no air conditioner. I don't have the money or means of other transportation to get it fixed. I checked the fuses, tried recharging it with freon or r134a and nothing seems to help. I don't believe the compressor is turning on when I turn on the ac at all. What's my best option?

Welcome to NICO!

First thing I'd do (which is easy for me to say because I have the equipment to do it) is to evacuate and recharge the system with the proper amount of refrigerant, that way you know you are good and won't damage anything by messing around with it. Too much refrigerant is just as bad as not enough, and you can definitely damage things if it's not charged properly. If you've tried recharging it, it's anyone's guess on how much refrigerant is in the system.

Next thing I would do is to bypass the low/high pressure switch with a paper clip or piece of wire to try and get the compressor to start. At least if you can get the compressor to start you'll know if the system works or not. If it does work, then you know you have an electrical issue somewhere, either from the buttons on the dash or a pressure switch. If it comes on but doesn't make cold air, then you know the compressor is shot.

I fixed my A/C with zip ties lol the knob to turn it to hot or cold might be broke from inside by the cable. Mine was and I just zip tied the cable down and my AC instantly started working. There is a few YouTube vids on it.