AC/Vents opening/closing on their own - Ford Truck Enthusiasts Forums



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AC/Vents opening/closing on their own

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Old 10-09-2015, 12:11 AM
F350GK F350GK is offline
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AC/Vents opening/closing on their own

Hello. I have a 1995 F350 crew cab. When driving the air/ac vents will stop working from the middle areas and only blow from the defrost vents.

What happens is at speed or under load the vents open/close on their own.

For instance. I can be driving at 60mph. then at 70 the middle/dash vents stop flowing and you can hear some sort of flap open/close and the air will only come out of the defrost vents. Let off the gas and usually the air flows as it should.

Not sure how to trouble shoot this.

any help is appreciated.
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Old 10-09-2015, 12:38 AM
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Welcome to FTE!!!


You have a vacuum leak!!

The most common vacuum problem on these trucks seems to be a white plastic line that runs on top of the A/C box under the hood, these like to get brittle and just crumble if you touch them, you should be able to repair it by replacing the bad sections with rubber vacuum line from the parts store. I hope this helps!!!
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Old 10-09-2015, 12:46 AM
F350GK F350GK is offline
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Thanks a lot for your reply. However. I'm not sure where to start or what to look for. When looking under the hood, would this be near or behind the battery? A little confused where to start.
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Old 10-09-2015, 01:11 AM
F350GK F350GK is offline
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I think I found what you are talking about. Hard to see in the photo but yeah, this line is brittle and broken. It runs into some type of wiring harness that looks pretty tough to get into. Could I just cut the the line, remove the bad section and replace with new? Or does the whole thing need to go?

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Old 10-09-2015, 01:13 AM
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Yep. You found it. Here's a helpful link:Vents are dead - FSB Forums
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Old 10-09-2015, 01:39 AM
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The factory line is usually in pretty good shape inside the harness, what you could do is get as close as you can to the harness and replace it with rubber line, then if trouble shows up later you can always go farther..

That's what I did, I replaced it as close as possible to the harness in 2005 and it is still working fine..... YMMV
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Old 10-09-2015, 02:05 AM
F350GK F350GK is offline
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Thanks for all the help. That line was indeed brittle and toast. Trippy how it was so related (mostly) to acceleration at EXACTLY 70mph. I'd get hot and slow down!

Looks like the line is good a few inches before the harness so I will start with replacing with a rubber line and see what happens.

wish me luck.
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Old 10-09-2015, 10:36 AM
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That white line? Maybe that's what's wrong with my temp **** being off alignment? That plastic white line in your photo is gone on mine. Completely toast
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Old 10-09-2015, 10:37 AM
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Quote:
Originally Posted by White 97 xlt View Post
Welcome to FTE!!!


You have a vacuum leak!!

The most common vacuum problem on these trucks seems to be a white plastic line that runs on top of the A/C box under the hood, these like to get brittle and just crumble if you touch them, you should be able to repair it by replacing the bad sections with rubber vacuum line from the parts store. I hope this helps!!!
Just read your second paragraph. Didn't see it at first. That's definetly bad on mine. Thanks
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Old 10-09-2015, 01:14 PM
F350GK F350GK is offline
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Next steps...?

So what's next... Removed the old bad line. Replaced with new. Same problem. Under acceleration defrost vent only. Off the gas all vents work fine.


Quote:
Originally Posted by choate View Post
Just read your second paragraph. Didn't see it at first. That's definetly bad on mine. Thanks
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Old 10-09-2015, 01:55 PM
F350GK F350GK is offline
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Hmmm

I unhooked the line completely and now it works perfectly..,,,????
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Old 10-10-2015, 12:42 AM
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Originally Posted by F350GK View Post
I unhooked the line completely and now it works perfectly..,,,????
I have,a different problem with the temp **** but yeah I just tore all the white line out of my truck too. I can't remember if I put silicone on the ends or not but my vents work fine.
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Old 10-10-2015, 04:18 PM
F350GK F350GK is offline
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choate; you just pulled the lines and plugged the ends of where they led? Or did you patch and replace your lines? I've now driven about 200 miles with mine unhooked and all systems work fine.

I'm afraid that maybe this controls something else too that I'm not aware of and could accidentally harm.
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Old 10-12-2015, 03:29 PM
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I don't think you are going to harm anything. I can't remember or not if I plugged them but I know I looked at that white line you have in the picture and I squeezed it because it looked like it was deteriorating and it basically fell apart in my fingers. Broke in half. Didn't notice any changes after that but I didn't know what it was. I thought maybe it was something the PO used to hold wires together or something not part of the actual system.
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Old 10-13-2015, 05:34 PM
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Don't notice any difference but I did fix mine today. Here is what you need. Fits perfect



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