A/C not cooling?

Originally when turning on the A/C or heating in my car it would make a noise. Like the fan had some issues or something. But the noise always stopped after a minute or so. NOW, of course with summer arriving, I am getting nothing. No more noise, no more air coming through of any sorts- hot or cold. My guess is it has either something to do with a motor or a fan or who knows. I know nothing about cars and just need to know where to start on this issue!

I have noticed that after about an hour of driving, the AC slowly starts to get warm. At first it works great, it is so cold I have to have the blower on low and slowly I will turn the blower up to full speed and it is still warm. My temperature gauge on my dashboard never moves to indicate that my car is overheating. Why does my AC get warm after an hour of driving?

I have noticed that after about thirty minutes of driving, the AC slowly starts to get warm. At first it works great, but after driving a while it turns warm. My temperature gauge on my dashboard never moves to indicate that my car is overheating. It has Freon. Thanks

Air Conditioning problem
1998 Kia Sportage 4 cyl Two Wheel Drive Automatic

lOW SIDE =40 PSI
HIGH SIDE=240 PSI
outside temp (FLORIDA)=92 degrees (F)
topped freon off since it was not blowing cold at all; pressures read as above with blower on HIGH.
THE low side ac pipe coming out of engine firewall(evaporator) is warm, other high side pie (ac line ) is HOT to touch. What could be worng. BOTH fans come on (ac condensor and radiator fan. Car NOt overheating).
Problem seems intermittent. Sometimes car will blow cold air (only when pipe coming out of evaporator(low side is cool to touch and sweating; otherwise, pipe gets hot again and will not cool car.
Both fans(AC CONDENSOR and radiator fan turn on). Car not overheating. PLEASE advise, thanks

When the car is running and the a/c is turned on it blows cold for about 10 min then switches to just normal air temp. Could this be the compressor?
Any other ideas?

If the compressor is there any issue with me changing it then having a tech evacuate the system pressure test and fill with freon?

Thanks