i just put a new ac belt on cus i didnt have one on for a while ever since i installd my unorthodox pulley set. now the ac only works while the idle is high. like while the car is driving but like at a redlight or wen im stopped the ac starts blowing hot air. wat could be the problem.

 

hows the tension of the ac belt.is it loose or ? if ac belt is tight.maybe your compressor is beginning to seize up.

 

Cars dont have AC for **** (even the brand new cars i work on) when they idle, and i'm guessing your underdrive pulley set is aggravating it. Or it might need to be charged. Any noise from the compressor while its running?

 

it makes a loud squealing noise

 

Squeal is loose belt or jammed compressor. Maybe your underdrive pulley set has the A/C tensioner maxed out, and can't tighten the belt anymore.

 

Both my civics have no problems when idling. Same with my 97 tacoma. BTW I have a 97 dx and a 99 SI.
What year car do you have? Perhaps it needs a recharge................