High pitch noise under hood 2003 ford ranger when excelarating

you must take off belt and check the belt tensioner pulley and the idler pulley by actually holding the pulley's in your hand and putting one finger through the center hole and spin it on your finger and also turn the inside with your finger this is so you can feel any vibration coming from it there should be 100% smooth feeling no catching in the movement if there is the inside has dried up and the ball bearings are worn and catching which will cause the load whining noise at high rpm's if you don't find this at those pulley's bearings there is one more to check after reassembly of the pulley's and belt start the engine and let it idle fi you still hear it now turn on the a/c and see if it gets worse/louder while at idle if so now it should get a lot louder when you step on the gas and this whining noise will be the bearing in the a/c drive pulley which needs to be changed you can do it yourself without taking the compressor out in some cases Good Luck Stephen you must take off belt and check the belt tensioner pulley and the idler pulley by actually holding the pulley's in your hand and putting one finger through the center hole and spin it on your finger and also turn the inside with your finger this is so you can feel any vibration coming from it there should be 100% smooth feeling no catching in the movement if there is the inside has dried up and the ball bearings are worn and catching which will cause the load whining noise at high rpm's if you don't find this at those pulley's bearings there is one more to check after reassembly of the pulley's and belt start the engine and let it idle fi you still hear it now turn on the a/c and see if it gets worse/louder while at idle if so now it should get a lot louder when you step on the gas and this whining noise will be the bearing in the a/c drive pulley which needs to be changed you can do it yourself without taking the compressor out in some cases Good Luck Stephen