No defrost

[Bozinator]

I have an 86 F150. Regardless of the settings on the vent selector I have airflow coming out the a/c vents all the time. I can move the selector from vent to floor or defrost and internal components do open and close (I can hear them). The only problem is the air never shuts off from the vent and the defrost air flow is almost non existent. This keeps the defrost from never fully thawing out the windshield in the winter time, regardless of how warm the cab gets. During my 10 minute drive to work in the morning, I have to adjust the temp because it gets too hot in the cab. Is there an easy way to access these internal diverters to adjust or determine which isn't sealing properly? I would rather not tear apart the dash to access the ventilation ducts but will do so if I have to. Closing the AC vents does not force more air out the defrost vents, just makes the vents whistle.

 

[Seabronc]

I would guess that the duct to the defroster vents is clogged with crap, probably leaves. The problem with the 80 - 86 intake in the cowel is the large slots that allow stuff like that into the system. It can be fixed by replacing the cowel with one from an 87 - 92 truck. It may only be clogged at the beginning of the duct or the whole thing may be full. The only way to make sure is to remove the dash cap so you can gain access to the duct.

Good luck,

>-

 

[rick2012]

I have an 86 F150. Regardless of the settings on the vent selector I have airflow coming out the a/c vents all the time. I can move the selector from vent to floor or defrost and internal components do open and close (I can hear them). The only problem is the air never shuts off from the vent and the defrost air flow is almost non existent. This keeps the defrost from never fully thawing out the windshield in the winter time, regardless of how warm the cab gets. During my 10 minute drive to work in the morning, I have to adjust the temp because it gets too hot in the cab. Is there an easy way to access these internal diverters to adjust or determine which isn't sealing properly? I would rather not tear apart the dash to access the ventilation ducts but will do so if I have to. Closing the AC vents does not force more air out the defrost vents, just makes the vents whistle.

I had to fix the door flap under the dash. (same problem)Its made of nylon i think, and it is just sort of folded to creat a hing effect!
I removed the center lower panlel then removed the proken door from inside the duct, made a temptet with cardboard. bought 2 very small brass hinges
from sears marked holes for card board and marked holes on duct housing for a good fit. then transferd to door and driled.
Allwas done on my back upside down #@%$. but it can be done. also sealed with thin foam insulation tape. Works better than new & will last longer than orignal.