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1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

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Old Oct 23, 2021 | 08:15 AM
  #46  
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The diagram below shows 5 vacuum lines to the control.


 
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Old Oct 23, 2021 | 08:19 AM
  #47  
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Here's the electrical part of the circuit.


 
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Old Oct 23, 2021 | 08:20 AM
  #48  
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Description of how the system works.


 
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Old Oct 23, 2021 | 10:10 AM
  #49  
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Good info , and hopefully no one has removed any of the op vacuum lines ! TR
 
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Old Oct 23, 2021 | 05:23 PM
  #50  
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Cool sounds like I am good on the vacuum front. as long as I can have defrost Im good went last winter without it and it sucked. Meanwhile since I'm waiting for the parts I replaced the blower motor and cleaned out inside there wow was there a lot of crap.
 
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Old Oct 23, 2021 | 06:28 PM
  #51  
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Originally Posted by Roost426
Cool sounds like I am good on the vacuum front. as long as I can have defrost Im good went last winter without it and it sucked. Meanwhile since I'm waiting for the parts I replaced the blower motor and cleaned out inside there wow was there a lot of crap.
By default the defrost should be on if there is no vacuum to the control as a safety.
If not getting air out the defrost at all I am thinking the door hinge broke and the door just sitting there.
You need to look this one over closer to see how the doors all work

Dave ----
 
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Old Oct 23, 2021 | 07:37 PM
  #52  
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Originally Posted by Roost426
as long as I can have defrost Im good went last winter without it and it sucked...
Was the air blowing out the four vents on the face of the dash, no matter what mode was selected? If so, this is for you:

https://www.ford-trucks.com/forums/1...oor-hinge.html

If you don't have time for the repair right now, that link also has details how you can easily block off the duct to those four vents and regain the defroster function.
 
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Old Apr 29, 2025 | 10:11 AM
  #53  
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Bumpity bump to an older thread. I finally had to replace the vacuum switch on the control panel, the same style as seen in post #27. How did you guys get the whole panel out? On mine, no matter how I tried, I could not get the foolish thing out from behind the dash. I had the radio, ashtray, and glove box removed but still no joy.

I was not able to separate the connector to the fan switch, and did not want to break it, so maybe that's what was limiting me. Such a miserable design, fitted BEHIND the opening in the dash. Seems it could have been designed just as easily to come out the front.
 
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Old Apr 29, 2025 | 12:20 PM
  #54  
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I am sure that is why the dash was busted up before I bought it as the owner sold the radio & HVAC control and could not get it out.
I had to take part of my non-AC dash to fix the AC dash.
As for how to get it out I cant tell you but have you tried to stand on your head yet

I should look into getting a good replacement for mine as you have to play with it to get the vacuum to switch.
To get air out the vents I have to go to AC first then to vent.
Dave ----
 
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