AC car problem

Hi guys. I have a Nissan Pulsar st 2001 model. The air conditioner was working fine when I first bought it. Then after a few days, while I was driving, I noticed the air con has turned off and I noticed that the AC button light is no longer on. I tried to turn off the engine and start again, but the AC refuses to turn on again. Later on at night when I need to drive again, the AC is alright again. But the next day, after maybe using the car for around 2 hrs, the next time I start the car again, the AC cant be turned on again. I refill the gas, 24 hrs was ok, but again problem... What can be the problem? When the AC is working, it is cold like normal.

4 common car ac problems
http://www.creechimport.com/
(919) 872-1999
1818 St. Albans Dr., Suite 106, Raleigh, NC 27609
https://www.youtube.com/watch?v=Vdyc3g25V7w&list=PLV_4gMKpSko9VQvJd8mWq3fseRJLZaUAe

car ac not blowing cold air
http://www.creechimport.com/
(919) 872-1999
1818 St. Albans Dr., Suite 106, Raleigh, NC 27609
https://www.youtube.com/watch?v=ieByHmCKRow&t=27s

Air conditioning is now a standard feature in most vehicle manufacturing. Having your car’s air conditioning go out suddenly can ruin your day fast. The most common causes of broken air conditioning are leaks or compressor issues. If your air is blowing cool but not cold, the problem could be a clogged filter, cooling fan problem or radiator trouble.

Common AC car problems are foolows :
1. Moisture
2. Pungent Odors
3. Low Refrigeration Level
4. Soiled Condenser
5. Mechanical Complications
6. Leaks
7. Compressor has cracked or damaged belt, defective clutch, inactive pressure switches or idle valves
8. Broken condenser

Source : http://techprotools.blogspot.com/