just got done body lifting my 98 4.0 4x4 and just noticed air ony comes out ofthe defrost vent no matter what setting switch is on... i looked under the hood and havent seen any vacuum lines off but i may have missed seeing a few... i have vacuum after the t coming from the resevoir, but havent made it any farther... anything else besides a line it could be??any suggestions or atleast can u point me in the right direction of things to check???

 

keep checking the vacuum lines

 

 

update. . . been all over the truck and basically cannot find a crack or break anywhere. still only works on defrost, however i am unsure if it was like this b4 the body lift because it is the summer and all i ever do is put the windows down... what is the next step?? im thinking buying a piece of vacuum hose and bypassing lines until i find the dead spot?? is there anything else i can check?? im stuck

 

Problem areas:

• Disconnected or cracked reservoir (eliminated)
• The plastic vacuum line from the reservoir to the HVAC plenum can contact the PS exhaust manifold and melt
• Vac leak under the dash going to any of the the three vacuum servos.
• The Pulse Vacuum Hublock system is a notorious leaker on 4x4's and the PVH shares vacuum from the reservoir with the A/C controls.

 

resurrection of an old thread because of still having only defrost.

95 4.0 auto XLT extended cab

OK, I have vacuum to the ball. I have vacuum on a hose which I found running on the PS frame rail back toward the underhood AC box. This line has a tiny bit of plastic fitting (obviously broken off of SOMETHING) on the end.

The AC was blowing out the vents when I went to work, only came out the defrost 8 hours later when I went home. How it broke while sitting I don't know but those are the facts.

Next question: it looks (lengthwise) as if it just goes up to the AC box at the bottom. No way to see or reach that area though. If I took off the PS front wheel, and the inner fender, do you think I'll be in a position to see WTF is going on? If I can find WHERE it goes, I don't have a problem repairing it, but where does it go is actually the issue.

Anyone run into this? Anyone have knowledge of what the bottom of the underhood AC box looks like, or if I'm barking up the right tree?

Thanks for any help!