dash vents not working

[04Powerstroke]

I just replaced my friends selector switch on his '99 for the same reason. Everything was staying on defrost.

 

[tkduty]

Same problem here

I replaced the little black vacuum distribution box on passenger side fender and it fixed the problem. If I had the a/c running and tried to go into 4x4 the a/c air would go from the dash vents to the defrost vents and no 4x. Part cost me 48.00 at Ford dealer.

 

[ckamp52]

well its kinda delayed but my buddy whos a mechanic looked at my truck last night to confirm what i had told him. we cant find any bad spots in the vaccum lines but the ac still thru the defrost and 4wd not working so dnt think its the switch but he noticed a possible vacuum pump on the drivers side in the engine compart e t he works on chevys and not a lot of diesels so he was wondering if this was the vacuum pump for this because if he un did the hose and blocked it off then it would produce vacuum and the ac would work so i guess thats the prob but was gna get more opinions and see if this would be covered under the warranty i have the extended 100k warranty

 

[rotorholic]

a/c stuck on windshield

ok i have the truck listed below and the other morning i was driving down the road and pretty warm and humid so turn on the air. well it was like 5 a.m so kinda half a** awake drivin to work and thot it was strange that the windshield kept getting condensate like the defrost vents were on but the swithch was on a/c so like i said too early for me to realize what was goin on . today i start headin home from work and turn on the air but after a few min it wasnt cool in the truck thats when i realized the actual a/c vents (dash) were not blowin but the defrost ones were going again...any ideas guys

I have the same problem, a/c stuck on windshield no matter where I set the switch to, I have a 99 f250 2wd...any ideas how to fix the problem?

 

[SMOKNZ]

Just noticed the exact same thing on my truck yesterday. I have manual hubs, so i know it isn't a leak on the 4wd. I guess start by testing the pump to see if it is pulling vacuum.

Bill

 

[DaveBen]

It is the pump. I have replaced a few on friends trucks, and all were the pump.

Dave

 

[Doghead]

Mike does the 6.0 have a similar electronic vacuum pump as the 7.3 and would it be located on the same fender?

I know in 99 F550 I had a passenger kick off the vacuum line under the dash by the footwell,wish I had a photo of that particular line for it's come off on many 7.3's.

I have the same problem on my 7.3 and I would like to see your photo so I can try to fix mine before the family vacation.

 

[rotorholic]

pump

It is the pump. I have replaced a few on friends trucks, and all were the pump.

Dave

It sounds like it, how do i test it before I go out to buy one? does truck have to be running or can I just turn the ignition on?

 

[rotorholic]

OK guys, try this to fix the problem, I went to unhook the vacuum line from the pump (facing the fender) the pump came apart and started working, It is o-ring sealed so it will be fine, maybe you guys will have the same luck......

 

[MONSTERPLOW]

nothin like an XL series