How to repair 2004 Ford Crown Victoria A/C will not blow from dash vents

no,the problem is the control head.common on these vehicles. or the vacuum diaphram motor behind the control head mounted on the heater box is weak. it could also be a vucuum leak on the hose going to the diaphram from the control head or an internal leak within the control head

i'd think that the vent adjuster knob/slider is not working correctly strip out the heater panel around the control knobs and check the vent direction is working properly either stiff operation so a little wd40 on the cable would probably do the trick or some thing causing the vent itself to not move

ford used steel control cables on some modles with plastic ends they break off and you lose control of the system nothing will work you can get the cable from ford or a wrecking yard other modles used vacuum controls a leaking vacuum line and the same thing no control trace the lines on the vacuum types and find the leak

There is no vacuum to the controls. Look for a vacuum hose that is no longer connected to the engine intake manifold and repair it.

those control units in the crown vics **** out all of the time. they're not cheap from the dealer, try auto parts stores for aftermarket or junk yards.
one trick we did with cabs was to pull the unit out and splice the black and blue vacuum lines together. that's great for summer, but you have only vent then.

Check the hoses underneath the cup holder area under the dash and make sure theres no obvious hoses disconnected. If they are ok, more than likely your selection switch is bad. You take off the plastic trim from around it starting from the passenger side of the car and remove the (4) 7mm bolts, carefully disconnect the colorful hoses and the wiring and replace the whole thing. I hope this helps

Hope I was avle to help, glad you up and going.

it either has a vacuum line on the back of the unit off or the control unit is bad

You have a vacuum leak. Defrost is the default postion(no Vacuum). Start by finding the small black vacuum line near the heater hoses at the fire wall under the hood.Trace it back, it should go to a square black reservoir . Not totally sure exactly where it is located on this model,shop manual doesn't show a very good pic, but it states to remove wiper arm and pivot shaft to remove it. You will see a second line going from here to intake manifold vacuum port. Make sure you don't have a leak there somewhere.

Chances are the electronic/digital HVAC control unit is bad. This same problem happened to me and I had to replace the entire unit. The dealer wanted to charge $800 for just the part! After I freaked out on them, they found a used one for less than half. Sorry, but there's no easy fix here.