GOL POWER 2004 AIR CONDITIONING

Hi everyone, I'm new to the forum. I have a question and I'd appreciate any help. A while ago, I noticed the timing belt squealing every time I turned on the A/C. Since it was winter, I didn't think much of it, but I would occasionally turn it on to give the air conditioning system a bit of a workout. Well, now that summer's here, I decided to change the belt. I also replaced the water pump, which had some play in the shaft, and the tensioner. The thing is, everything's new, but the belt keeps squealing, even without the A/C on when the car is cold. Once it warms up, it stops. But what I find most strange is that when I turn on the A/C, it squeals like crazy; it sounds like the belt is going to fly off. The noise it makes is incredible. I stopped to watch, and sometimes it sounds like the A/C pulley is seizing up and the belt is spinning on it. But the worst part, or the best part, I don't know, since it's both good and bad. Inside, the air conditioning cools. Now, when it's at low RPMs, this happens: if I... I'm driving, and when I accelerate, it stops making the noise, and the air conditioning works perfectly. But when I decelerate, the squealing starts again. It's driving me crazy; everything is brand new. If anyone can give me some guidance or any idea what it could be, I'd appreciate it. Thanks.