Air only blows on defrost???
Got Diesel?
Joined: Jan 2004
Posts: 4,345
Likes: 21
Here is the box top showing the new Ford/Motorcraft part number for the Pulse Vacuum Hub Solenoid Valve.
Part #: 7C3Z-9H465-A
I paid $48.25 which was the preferred customer price at my local Ford dealer.
It took 10 minutes (maybe less) to remove the old valve and install the new one. There is 1 electrical connection, 2 vacuum lines and 2 screws that hold it on... bingo... I now have 4WD and my AC blows out the front vents and not the defrosters!!!
I saved paying 1 hour of labor... but it was so easy to fix, I just had to do it myself... and so can you!!!
Part #: 7C3Z-9H465-A
I paid $48.25 which was the preferred customer price at my local Ford dealer.
It took 10 minutes (maybe less) to remove the old valve and install the new one. There is 1 electrical connection, 2 vacuum lines and 2 screws that hold it on... bingo... I now have 4WD and my AC blows out the front vents and not the defrosters!!!
I saved paying 1 hour of labor... but it was so easy to fix, I just had to do it myself... and so can you!!!
Fleet Mechanic
Joined: Oct 2007
Posts: 1,712
Likes: 18
From: Henderson, NV
Just the thread I was looking for... has anyone had their Vacuum Pump vibrate like it wants to jump out of the engine compartment? Mine has been doing this intermittently for the past week or two. Its a very loud buzzing noise. Is there a way to take it apart and fix it (wanted to ask before I tear it apart...lol). Thank you.
Got Diesel?
Joined: Jan 2004
Posts: 4,345
Likes: 21
Just the thread I was looking for... has anyone had their Vacuum Pump vibrate like it wants to jump out of the engine compartment? Mine has been doing this intermittently for the past week or two. Its a very loud buzzing noise. Is there a way to take it apart and fix it (wanted to ask before I tear it apart...lol). Thank you.
Senior User
Joined: Aug 2009
Posts: 226
Likes: 0
From: fredericksburg ,va
woah hold the phone i just went thru this and i spent hundreds. my machanic was under the hood for a moment and saw a leak in the air storage right in front of the battery, look around that, its big and black on left side . i bet you got a leak or the vac line to your locker hubs, maybe ice damaged something but dont buy anything yet cause there are no refunds.
New User
Joined: Mar 2005
Posts: 6
Likes: 0
stuck defrost
Mine is doing the same thing.... If I shut truck off it reverts to only defrost... I have fiddled around and figured out if I shut off heater/ac all together before i turn truck off it will work on panel setting after restart... Also if you forget to turn off climate control before you shut off truck... You can select panel floor or both and run the temp setting all the way to 90 and back down to 60 and AC switches to panel from default defrost????
Any body have any ideas????
I have looked behind glovebox and vacuum lines dont look kinked... It will switch but only after fiddleling with it running temp up and down everytime....????
Any body have any ideas????
I have looked behind glovebox and vacuum lines dont look kinked... It will switch but only after fiddleling with it running temp up and down everytime....????
Got Diesel?
Joined: Jan 2004
Posts: 4,345
Likes: 21
Mine is doing the same thing.... If I shut truck off it reverts to only defrost... I have fiddled around and figured out if I shut off heater/ac all together before i turn truck off it will work on panel setting after restart... Also if you forget to turn off climate control before you shut off truck... You can select panel floor or both and run the temp setting all the way to 90 and back down to 60 and AC switches to panel from default defrost????
Any body have any ideas????
I have looked behind glovebox and vacuum lines dont look kinked... It will switch but only after fiddleling with it running temp up and down everytime....????
Any body have any ideas????
I have looked behind glovebox and vacuum lines dont look kinked... It will switch but only after fiddleling with it running temp up and down everytime....????
Defrost is the default safety measure in case it happens in the winter and one needs to keep one's windshield free of frost/snow so you can see!!!
Probably a leaking vacume line to your 4X4 hubs or the solinoid valve I mentioned a few posts above???
New User
Joined: Jul 2010
Posts: 2
Likes: 0
Vacuum hub
Here is the box top showing the new Ford/Motorcraft part number for the Pulse Vacuum Hub Solenoid Valve.
Part #: 7C3Z-9H465-A
I paid $48.25 which was the preferred customer price at my local Ford dealer.
It took 10 minutes (maybe less) to remove the old valve and install the new one. There is 1 electrical connection, 2 vacuum lines and 2 screws that hold it on... bingo... I now have 4WD and my AC blows out the front vents and not the defrosters!!!
I saved paying 1 hour of labor... but it was so easy to fix, I just had to do it myself... and so can you!!!
Part #: 7C3Z-9H465-A
I paid $48.25 which was the preferred customer price at my local Ford dealer.
It took 10 minutes (maybe less) to remove the old valve and install the new one. There is 1 electrical connection, 2 vacuum lines and 2 screws that hold it on... bingo... I now have 4WD and my AC blows out the front vents and not the defrosters!!!
I saved paying 1 hour of labor... but it was so easy to fix, I just had to do it myself... and so can you!!!
I know mine is bad when i turn on the 4X4 it loses all vacuum with the line to the hubs blocked. How much vacuum is the pump suppose to create mine is at 15 thanks
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Got Diesel?
Joined: Jan 2004
Posts: 4,345
Likes: 21
There can be several causes... but the solinoid is the main one to go bad... so I tried it first.
1) Bad solinoid
2) Leaking hose (before or after the solinoid).
3) Leaking hub (one or both of them).
I figured I would install the new part and try it out... if not... return it and claim I found a leaking hose and it was not the part I needed (all within 1 hour)... so the part is still clean and all is well. If it works... the great... it works!!!!
Posting Guru
Joined: Oct 2005
Posts: 1,285
Likes: 1
Low/no vacuum will cause the htr. & a /c to default to defrost only.
Vacuum pump failure and vacuum line leaks are a common problem.
The vacuum pump is on the right (pass.) side fender.
Make sure you have power to the pump, if not check fuse.
If you have power,disconnect vacuum line and feel for vacuum.(hear pump run)
If no vacuum, replace pump. If you feel vacuum, then there is a leak.
Most common area for leak is vacuum hoses to; and front hubs (hence question about 4x4 earlier).
If pump is good, and no leaks,time to go inside the dash (doubtful).
Vacuum pump failure and vacuum line leaks are a common problem.
The vacuum pump is on the right (pass.) side fender.
Make sure you have power to the pump, if not check fuse.
If you have power,disconnect vacuum line and feel for vacuum.(hear pump run)
If no vacuum, replace pump. If you feel vacuum, then there is a leak.
Most common area for leak is vacuum hoses to; and front hubs (hence question about 4x4 earlier).
If pump is good, and no leaks,time to go inside the dash (doubtful).
Thanks
2nd Gear
Joined: Jul 2012
Posts: 2
Likes: 0
Thanks everyone for these detailed information about the Vacuum system. I had the same problems with my vacuum pump running constantly.
I was able to find my problem reading this thread and testing the different components.
My pump was working fine, shutting off after I disconnected the reservoir and plugged the tube, the reservoir held a vacuum, so I had to have a leak somewhere else.
I was lucky finding the culprit in the engind compartment. Right behind the oil filler, one of the vacuum tube branches attaches to a device (sorry I am not that knowledgeable with this yet, still am learning) and that had been pulled off. I just had my oil changed at a large retail store here in town.
I am glad I found this thread about this, otherwise I would have been looking all over the place. Thanks for all the wealth of information in here!!
I was able to find my problem reading this thread and testing the different components.
My pump was working fine, shutting off after I disconnected the reservoir and plugged the tube, the reservoir held a vacuum, so I had to have a leak somewhere else.
I was lucky finding the culprit in the engind compartment. Right behind the oil filler, one of the vacuum tube branches attaches to a device (sorry I am not that knowledgeable with this yet, still am learning) and that had been pulled off. I just had my oil changed at a large retail store here in town.
I am glad I found this thread about this, otherwise I would have been looking all over the place. Thanks for all the wealth of information in here!!
New User
Joined: Jul 2012
Posts: 7
Likes: 0
Check the small vacuum line that hooks up to the cylinoide rite above the oil filler tube. The lil rubber boot gets hot and cracks and u loose vacuum to the a/c. 2.00 part quick fix. Go to auto zone and get a multi pack. I suggest the 90 degree one.
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