Air conditioner not working?

I bought this car used and the air-conditioning was not working. I am student and want to know the cheapest way to fix the this. Please help.

I bought the camry le during the winter so I didnt know the air conditioning did not work right. I did try the air conditioner and when I tried it it worked fine. Well summer came around and I notieced that as it works great as long as the outside temp is below 70 degrees. When its hotter then 70 degreesit it doesnt blow out cold air. In fact it blows warm air. If you have any insite as to what the problem is I could really use it. Thank you.

Air Conditioning problem
1992 Toyota Camry 4 cyl Automatic 171640 miles

My AC light is blinking and blowing hot air, I put a charge on it and it took the whole can, but still blowing hot air.

I have a '92 Camry station wagon. 4 cyclinder. 260,000 miles. I have the 134A system. Air-conditoner cools for about 30 minutes, then gradually turns warm. I will let the car sit for a few hours, start out again, and the whole thinsg starts over again. Cool to warm. My mechanic keeps adding stop leak, but we can't figure out the problem? Thanks

Yes, we add a can of 134a stop leak every month, but we can't find the leak. Can we deduce that since the air-conditioning it works for at least a half hour that it's not the condensor or the compressor?

I am not getting any pressure on my gauges which tells me that I do not believe the air conditioner compressor coming on. Could you show me the electrical part of it the pressure switches? Any necessary information relays, fuses? I really appreciate you in this matter.

Yes Joe, I do have static pressure with the engine off and everything off it's reading kind of low, but it do have a reading on it so I do believe it's not the high pressure switch I can rule it out and I think it might be the low pressure switch or for some reason the compressor is not engaging cycling cycling on and off.