The Blower Motor DOES NOT run when in the VENT position.
VENT just opens up air flow from the vent on the cowl into the cabin.
Good explanation here ..... Thanks to
Wrangler Haven
http://www.wranglerforum.com/f218/yj-heating-system-explained-68618.html
Here is the explanation from that thread .......
Moving the slider into the Vent position does a number of things all at once. It shuts off the blower motor.It opens the passenger Vent Gate for the first time. And it opens the left Cowl Gate for the first time. The Defroster Gate remains unchanged and the Blend Gate (although it can be moved) serves no purpose since there is no airflow past the passenger Vent Gate. When this gate opens it blocks 99% of the airflow into the blower motor and the rest of the system.
The left Cowl Gate (the most difficult to see since it's deep within the dash above and behind the speedometer) allows fresh air directly into the cab bypassing the entire system.
It should also be noted that the right Cowl Gate defaults to the open position when the vacuum motor, which controls it, looses vacuum. This happens hours after the engine is shut down regardless of the dash slider positions. This typically is not a problem even in the rain as long as the Cowl drain tube remains clear. Should the drain tube become clogged, the Cowl can partially fill with water which can seep past both Cowl Gates. The Cowl drain tube is located within the engine compartment to the right of the battery.