Windscreen air vent not blowing air

What make an model an year vehicle do you have ? The air blows out of the floor vents an center vents but not defrost ? Possible mode actuator , stuck mode door ! There is a door inside the heater / A/C assembly that directs the air to the desired position . These doors can be moved by a vacuum operated actuator or an electric motor . Sometimes thing's put on the dash end up inside the heater box , fall through defroster vent ! Pens , pencils etc.. Depends on the make vehicle an system , manual , or automatic climate control . Some of the newer vehicles the HVAC system as it is called , the control panel is a electronic control module an can store DTC'S - diagnostic trouble codes !

faulty switch/knob

air con switch in dash or fuse

blower motor fuse, blower motor, or climate control

Fairly common fault on Electrically controlled valve on the hearer inlet pipe. Replacement is only cure. Good Luck

Follow the link below for the blower fix:

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its your evap drain clogged look under hood at passide near bottom of firewall you may need a peice of wire to unclog it or at the shop we stick a air blow gun to clean it out cheap fix may have to get under the car to see it

you either have a clogged ac line or you have a vacuum problem that will prevent the correct vent doors to open to allow the air to enter

Either the door that controls the flap that either sends the air through the defrost or the regular outlet is stuck or not working. Some of them work off of a cable and others work from vacuum. Not sure which the ford escort uses but usually you are able to hear the flap move when you go from defrost to regular cabin vent. Or possibly the air duct hose has come off that sends the air through the cabin. Good Luck and hope this helped a little.

your heater core is most likely stopped up.