AC Blowing through defrost only when accelerating.
06-04-2012, 04:28 PM
#1
Junior Member
Thread Starter
Join Date: Jun 2012
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
AC Blowing through defrost only when accelerating.
2001 F150 Lariat 5.4L...I've found lots of post on here regarding this issue and have replaced several vacuum hoses that had holes or cracks in them. However, I am stumped by where the vaccum hose in the picture should go? Does it get connected to anything? It is bundled with a red and blue vacuum hose and those hoses connect to the 2 manifolds on the firewall but the black hose is not connected to anything nor can I find where it attaches...driving me crazy!!! Can anyone help me out?
Last edited by tnicarry; 06-04-2012 at 04:32 PM.
07-03-2012, 03:25 PM
#3
Junior Member
Join Date: Jul 2012
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
tnicarry,
Forgive the previous post with only pictures. This is my first time posting.
I was just trying to help by showing the manual control on my '01 F150 and the black vacuum supply line that I repaired by splicing and inserting both ends in a new chunk of larger tubing. It is located between the battery and the firewall.
Prior to repair, my problem was that the air blew only through the defrost vents. It didn't matter which selector position (right ****) was chosen.
This problem was easy to spot once I started looking in the right place.
Hope this helps. I scoured the forum before going to work. The posts and pics were very helpful. Thanks to everyone. Regards, dcg0513
tnicarry,
Forgot to mention, the black line is the vacuum supply for the right hand control selector on the dash. It goes through the firewall and supplies vacuum to one of five colored vacuum lines connected to the back of the control selector. Those lines then control the various vent doors. I learned on the Forum that for safety reasons, when no vacuum is available from the supply (due to hole/leak, etc.), the default position is to route all air to the defrost vents to ensure the window is clear for visibility. Makes sense to me.
In the pics you can see that the black line is plugged into a main vacuum supply line which I believe comes over from the manifold.
Forgive the previous post with only pictures. This is my first time posting.
I was just trying to help by showing the manual control on my '01 F150 and the black vacuum supply line that I repaired by splicing and inserting both ends in a new chunk of larger tubing. It is located between the battery and the firewall.
Prior to repair, my problem was that the air blew only through the defrost vents. It didn't matter which selector position (right ****) was chosen.
This problem was easy to spot once I started looking in the right place.
Hope this helps. I scoured the forum before going to work. The posts and pics were very helpful. Thanks to everyone. Regards, dcg0513
tnicarry,
Forgot to mention, the black line is the vacuum supply for the right hand control selector on the dash. It goes through the firewall and supplies vacuum to one of five colored vacuum lines connected to the back of the control selector. Those lines then control the various vent doors. I learned on the Forum that for safety reasons, when no vacuum is available from the supply (due to hole/leak, etc.), the default position is to route all air to the defrost vents to ensure the window is clear for visibility. Makes sense to me.
In the pics you can see that the black line is plugged into a main vacuum supply line which I believe comes over from the manifold.
Last edited by dcg0513; 07-03-2012 at 03:40 PM. Reason: Add more info
07-11-2015, 09:40 PM
#4
Junior Member
Join Date: Jul 2015
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Open black vacuum line
I have found others discussing finding this same open line and mine has it too. I think it is supposed to be open. I traced it down to my front differential. Perhaps it is designed to be open to allow the vacuum to release when taking it out of 4WD. I do not know.