Hi, I have a problem with my 2002 Tacoma 4x4,, went out of town for 3 1/2 weeks and when I returned and drove it I found there was a problem with the air flow from the air conditioner.  (It worked perfectly fine before  I went out of town.)  There seems to be little air movement out of the vents in the cab and there is a low roar when I turn on the air conditioning. I am suspecting some type of blockage, but unsure exactly where to look. I have  had the truck two years and am the second owner.  Everything else is in great shape so I haven't had any other issues to deal with and am relatively new to the Toyota product, though I have always done most of my own work on other vehicles.  Any help or pointers would be much appreciated.