Well it had to happen , my ac was working fine untill I started my truck and the ac is now making a loud humming or vibrating noise. Happened all at once, never did this before. The ac is still works,but when it's on high, it's loud It gets louder the more I turn it up. Anyone elese ever had this problem?
Thanks.

 

Yup, exactly the same problem on my 03!

Look under the glove box, there is a blower motor. I traced the noise to that motor. I was going to pull the motor ( only 3 or 4 screws). No need to pull the motor, all screws were loose, real loose. I tightneed them.......no more noise. Hope this simple fix will solve your problem.

8Valve

 

The other possibility is the recirulation door may have broken and dropped into the fan.

If you remove the glove box, you can see the recirculation intake grille, and if set to fresh air, you would be able to see the door if it is still in place.

 

Thanks guys, I will try that

 

If it is a broken recirc door, remove the blower motor and the recirc door should be laying right there in the hole. Wiggle it around just right and it will come out of the hole.

From there, it's up to you whether or not to fix it. There are those that have chosen not to replace it.