Broken A/C

Apparently I'm having a very common problem with my Intrigue, my A/C is having issues. The lowest fan setting does nothing and on the rest the air works ony part of the time. The a/c light will blink and go off and then it won't blow cold air. Sometimes it will turn back on or if I change the fan speed it will work again. Can anyone tell me the source of the problem and the most cost-effective way to fix it?

Also, can I install an auto climate control into my manual '98 Intrigue?