A/C Does not work well

[Mike 88GT]

I'm certified in a/c and refrigeration. And your problem sounds like plan and simple like your low on freon. A way to tell is sometimes theres a sight glass near the condensor and when the a/c is on you can watch that. If you see nothing but liquid, your good. But if you see bubbles, your low. Or place a thermom. in the vent and read the temp coming out. It should be around 55 deg. or lower. You can buy a recharge kit from most auto stores for pretty cheap. Just make sure its R12 refrigerent. Good luck.