belt shakes and makes noise when AC is on

[chev1500man]

I repaired the AC compressor twice and replaced the belt & 2 different belt tensioners with no success. When the vehicle is on and in park, the belt is working properly. If the AC is turned on while in park the serpentine belt wobbles a little and makes like a vibration noise. When it is engaged in drive, it goes away. Also, now sometimes, it has started to wobble in the same way when it is engaged in drive. All the bolts are tight and all parts have been replaced. The AC compressor is cycling normal and belt tensioners and belt are new. Thank you.

[locknkey]

You may have too much oil or R-134a in it, have you done a moisture pull fro mthe dryer? The way you're describing seems like its the above solution to your problem, but it wouldn't hurt to check the high and low side pressures of the freon...before it locks up and snaps that surpintine belt in two pieces or smokes it.

[chev1500man]

thanks for the reply. I was out of town. Pressures are ok, but I will try lower them to see if it improves. Oil I dont know because a shop did it and they are not going to admit to any problems vaccum and filling lines. I may take it in somewhere to see the oil &fill it again. thanks for the help