ac trouble

the ac in my 05 hardly works. when on full blast it hardly blows any cold air. the compressor kicks on and off but when it kicks on there is a terrible drone/whining noise inside the car. I put the car in park with the blower on high and rev the engine to 2500 rpm, pushed the ac button. when it kicked on the rpm dropped dramatically and the droning noise. its also getting horrible gas mileage. ideas?

The idle is normal. Our cars don't make much power and with the a/c on its reduces a lot. As for the drone can you here it under the hood? If not it could be your blower motor as for gas mileage that goes along with the power it takes from the motor to use the a/c plus try to keep the engine useful on the highway. Hope this helps.