You can pull the blower motor and fan for the AC/Heat pretty without too much trouble fortunately. Rough steps as I recall them:
-remove the glovebox, I just pull the two phillips head screws that are on the hinges and then unlatch the glovebox and drop it down. don't even have to empty the contents to remove it
-remove the 3(?) screws holding the motor in place and start to lower it down (this may be out of order)
-pop the linkage rod for the recirculation flap out of it's socket and disconnect it. I think this is a pretty standard connection type and the same as what you find in the doors etc. where the socket rotates to clip or unclip from the linkage rod/shaft so that the end can then slide out of the socket...
-unplug the motor harness/plug and then lower/wiggle the motor and fan out
I'm sure the FSM and other posts on here would do a better job of guiding you but if you head out to your truck with basic hand tools and a flexible back you should be able to get the motor out pretty quickly and easily.
On my truck the cause of my squeak was a plastic bag of all things. I'm not sure how it caused the squeak but I cleaned it out of the fan and reinstalled and the squeak was gone, no oil added. I recommend you pull the fan and clean/inspect as a next step and if it's really dirty you may not need to try to oil what I assume are bushing in the motor (just a guess). It's easy to pull the fan off of the motor for washing but I don't recall how hard it would be to dig deeper, though I'm sure others on here have.
Also, when the fan motor is off you have decent access to the evaporator core / box. I was able to clean debris out of the box and spray coil cleaner on mine via the air inlet hole that the fan/motor fills.
