vents
New User
Joined: Sep 2003
Posts: 7
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vents
i have an 85 F150 and i dont believe it would be a vaccum line I can only think of two things. First of all open the hood and on the firewall on the passenger side should be a black box with a wire sticking up with several bends in it and there should be a cable attached to it. The other thing is if that cable is on the wire sometimes those wires seize up and from inside the pickup it will seam to be moving when it really isnt. I would suggest noting the position of the cable and wire and then go in the cab and move the defrost lever and then check the cable position again. If it hasnt moved then pull the cable off and see if the wire moves. Then see if the cable moves. I suspect that either the cable is off of the wire or your cable is seized. If the cable is seized you could maybe put penetrating oil in it and work the **** in the cab and free it up or you might need a new one.
Senior User
Joined: Dec 2002
Posts: 149
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From: Huntsville USA
For some more ideas, check out this thread. I had a similar experience. I've typed it out once, didn't feel like typing it again. 
http://www.fordtruckenthusiasts.com/...hreadid=154883
http://www.fordtruckenthusiasts.com/...hreadid=154883
Senior User
Joined: Jul 2003
Posts: 208
Likes: 1
From: Meggett SC
Defrost is the default position of the ventilation system. My 84 F150 had a broken flapper hinge. There is a large flapper in the vent duct worked by a vacuum solenoid behind the heater controls and a little to the left. When you move the lever to vent you can watch the solenoid work with a flashlight by looking between the glove box and the heater controls. If the solenoid works then the plastic hinge of the flapper may be broken.
Its hard to get it out, But i was able to fix mine.
If the vacuum solenoid is not working check the vacuum line in the engine compartment on the left side above the vent fan motor
I have found mine cracked in half.
Its hard to get it out, But i was able to fix mine.
If the vacuum solenoid is not working check the vacuum line in the engine compartment on the left side above the vent fan motor
I have found mine cracked in half.
