OK here we go. If the selector switch will not work i know the problem. if all you feel is the air blowing from the vents by the windshield it is vacuum related. this is what i found on my 2003 Ford Windstar. first pop your hood and open it up. Next remove the windshield wipers and place in a safe place, note the locating, or angle of wiper arms before you remove them. there are two deck covers which i call them on the bottom of the windshield that have to be removed or moved. using a Phillips head screw driver, remove the little black screws and black plastic guard under the windshield. under it will be a metal deck plate which will also need to be moved in order to see the vacuum lines behind the cabin air filter on the passenger side. I found the vacuum line that connects to the cabin air filter housing was disconnected. simply plug it back into its little nipple and your selector switch will work about 10 seconds after you start your vehicle. If this doesn't fix your problem there might be another vacuum line disconnected of you have other problems i didn't have. a good place to start is under the dash inside the vehicle. sometimes these lines can get damaged and or broken causing problems. I hope this helps a lot of people out there.
something has to be blocking the vents.
Heater core
my 1999 winstar was doing this and it was the blend door
The wiring, switch or blower has failed.
After Unplugging your ac check the opening of the front with something that you can slide inside the opening like a tooth brush. Do it gently. There is a blower behind the opening. At times a lot of dust particles get stuck in the blower ( its like a long roller ). All you have to do is clean this blower with the brush. If you could post the brand of your Ac, Type and capacity, It will be more helpful. Generally its not difficult after you have seen it being done once. Tell me if it works.
heat works in back not in front front blows hot for a few mins then cold
The front blower should have a resister to change the speeds. It is usually mounted close to or on the back of the blower motor.
If you set the directional control for the air to flow thru the ac-vents only, you'll probably notice that the fan is set on low or high, and stuck there - regarding the front blower motor. The rear probably works normally. If this is the case, it's probably the heater blower motor RESISTOR that needs to be replaced. If not, then you may need a new front heater blower motor. Hopefully it's not the switch, they're expensive.... Good Luck. When the front blower motor is stuck on low or high, it's ususlly the blower motor resistor.
Failed blower motor, resistor or switch.
Check the fuse box. The front and rear blower motors are probably on different fuses.
Either you have a faulty blower fan in the front, or power isn't getting to it.
sounds like you have a bad blower motor.. i just replaced one on my 02 deville for the same reason with the same symptoms