AC button the fan speed drops dramatically

When I push the max ac button on my 2005 camry the fan speed drops dramatically where as I cannot even feel air blowing from my vents. It used to increase fan speed, now it reduces to barely anything. Whats wrong? The dealer checked resistors and said they are all fine. But while I was driving I had max ac button on and then all of a sudden I lost high fan speed. It used to blow fast when the button was pushed and not barely at all. I here an increase in speed in the blower under the dash but not at the vents.