Non-stop on/off air compressor/Hesitation/Warm air

I have a 2004 Nissan Xterra with 41,000 miles. A few months ago I noticed a clicking noise that I had never heard before. I found out that it was my air compressor turing on and off. It turns on and then right back off, so it is a continual clicking noise. If I have the AC on when I am driving the car hesitates every time the compressor clicks on or off. It feels like my car is holding back every few seconds. Like someone tried to pop it into neutral but then decided to put it back into drive. My air conditioner is also lacking in its ability to blow out cold air. When I turn the AC on it feels like it is blowing room temperature air out. I thought maybe, just maybe I might be low on freon, so I refilled it and that definitely wasn't the problem. The clicking noise that the air compressor is making when it turns on and off is driving me insane and the room temperature air is waaaay too hot for me. I live in Florida and I have noticed that I am better off driving with the windows down than sweltering with the 80 degree air blowing in my face from the AC. If anyone has any idea what could be wrong, please let me know! Thanks!