The mechanism is on the passenger side of the heater unit a couple inches back on the right side. It is connected by cable to the control unit on the dash in the vent setting. If it doesn't work, it is likely one of the clips securing the cable to the heater housing, or the control unit, is damaged. If you do not need the vent, then disconnect the cable from the lever on the heater unit and manually close it using the lever. Kind of a tight spot but easily done. Otherwise, you must replace the cable. Good luck finding one as they quit making them.
between the hood and the windshield
It is under the wiper cowl. The painted piece in front of the windshield.
The motor sits under the cowl at the base of the wiper arm.
If its not mounted on the firewall, then you'll probably need to pull the cowl vent panel located between the windshield and the hood and it will should there.
On a Jeep Wrangler it is located in the cowl. Take the wiper arm(s) off first. Undo the bolts at the top corners and the bolt in the bottom of the bracket at the bottom corners. You may need to unscrew the visor. Then fold the windshield right down onto the hood . Presto! There are your motors.
heater resistor will be located in the upper section of the plastic trunking for the air flow from the cowl grill. It should have 3 prongs fitted for the wiring and normally 2 screws to hold it in place. Remove the screws and the resistor should pull right out.
The windshield needs to be folded into the down position to access the wiper motor. There are a couple cut-outs in the metal of the cowl that allows access to the wiper motor & linkage. There are release bolts on either side of the windshield & of course the top needs to be off.
Rotating chimney cowl, rotating chimney cowl, spinning cowl, revolving cowl,
First remove the windshield wipers, pry up the small tab near the vent cowl on each wiper. Then remove the screws that hold the vent cowl, pull the vent cowl off and you will see the wiper motor on the driver side
04-06 LJ's and 97-06 TJ's do not that I'm aware of but there is one aftermarket solution that I'm aware of from www.offroadtrailtools.com. It's called the clean air scoop and integrates a filter into a scoop for the cowl intake. Here's a direct link to the part: http://www.offroadtrailtools.com/shop/index.php?l=product_detail&p=88
You need to get the windshield folded down. This means remove the top, then the front sport bar members. On each side is a bracket that holds the windshield upright. Remove screws to allow windshield to be folded down (gently) on the hood. The wiper motor is in the top of the cowl & should easily be visible. It might not be easily accessible, but it will be visible.
You need to remove the cowl... the piece between the windshield and the hood. There are four screws in plain sight and two hidden by the weather strip. Of course, you must remove the wiper arms prior to removing the cowl. To remove the wiper arms, look for a little tab on the bottom of the arm. Use a screw driver to move the tab outward. You shoudl then be able to remove the wiper arms. To remove the wipe motor you must remove the entire wiper module. There are three bolts that need to be removed.