Hello I am new to the forum. I was wondering if any one knows where a particular vacuum line goes to. First off, I have a 02 F150 XLT 4x4 with the 5.4 engine it also has AC. My truck has 128,xxx miles on it. I have found a broke vacuum line coming from the vacuum reservoir behind the battery, it is not the lines attached to the bottom but the line that attaches to the top port the line looks like 1/8 diameter line that hooks to the top of the vacuum reservoir. I have no idea where this line is supposed to go to. The other issue which I am sure is tied to this, is when I accelerate my panel setting goes to the the default defrost setting. Any help would be appreciated.

 

What color is the line?

 

The vacuum line is black. There is another line that is black connected to the bottom connection also but it is a bigger diameter.

 

Hmmmm. Have u took it to a shop to have it smoked or anything?

 

The lines is completely broke and just hanging beside the battery tray so I do know where it is suppose to go. If I could find the other end I could fix it. It would make it an easy fix if I know where it is suppose to go. I have not found where the rest of the line is at. So if no one knows where it goes I will have to take it in and have someone else try to find the other end of it.

 

I am having the same problem with vacuum. When I accelerate the air from the vents goes to the defrost. When I let off the accelerator the air returns to the vents.

So far, I've been told to check the vacuum reservoir "tank" that is somewhere elusively in the fender? What the heck? Do I need to take the wheel well liner out to find this creature? or does it even exist?

 

The broken vacuum line is the reason the AC systems defaults to defrost. Fix it and you AC system will be working again. Look for line or hole in firewall to attach it.

 

The vacuum reservoir is located on the back of the battery tray. If you take the battery out is located on the fender side of the battery tray. It slides into the tray. You can access it by taking off the battery tray for bolts two that are down and two bolts that attach to the fender. Then when you take it out it will be easy to access the vacuum reservoir. If you only have to remove the battery and the tray to access it. I hope this helps.

 

Are there two vacuum lines that enter through the firewall? I already located the one that goes through the firewall. I did not see any lines hanging underneath the dash. I still have not figured out where the other line goes. I think having the line open is what is causing the vacuum to be weak which in turn makes the AC default to defrost as you mentioned. Thanks for the reply.

 

Should be only one line going thru the firewall to feed the servos, engine side vacuum source to maybe check valve, then on to the reservoir and out to the line going thru firewall.