My 2001 ford tarusas ac want come out the vents only defrost?

My 2001 ford tarusas ac want come out the vents only defrost?

Your vents are close? Does the vent control work? Take it in for a check up.

Do a google image search for "2001 taurus vacuum hose diagram". See the types of vacuum hose disconnections and breakage that can cause your issue. Then look under your hood and try to find the problem, correct it (reconnect hose, splice in a length of hose from the auto parts store, whatever) and the vent selector will work again.

Many times the blend door actuator goes bad. Often times, before the part fails, it will make a rhythmic snapping noise, like someone snapping their fingers to a beat. The actuator is the little part that sits on top of the air exchange box behind your dashboard and moves the little blend door. Depending on the position of the door, air is routed through the air box into the cabin of the car. It tends to fail in the defrost position.
Although it is possibly a vacuum leak in the engine compartment causing your problem, it is highly unlikely. Check it out anyway. Why? Because it is a heck of a lot cheaper to fix than a blend door actuator.
Now for the real bad news. In order to repair a blend door actuator you must remove the entire dashboard. While the part itself is relatively inexpensive (about $50), the labor putting the new part in is going to be extreme. I believe that the job rates at 8 or 9 hours which is about $800 to $900 worth of labor.
If your mechanic does replace the actuator, replace the heater core while you are in there. The heater cores are notorious on Fords for failing, and to get at that, you have to remove the dashboard as well (the parts are right near each other). It makes zero sense to have your A/C blend door actuator replaced, just to have the heater core fail next winter. Especially since a new heater core will only set you back about $40.
Seriously, though, if it were my car, I would sell it and get something else.