I did a few searches for what I'm asking but what used to be a pretty quick search now takes forever on this website so I lost patience and figured I'd just ask. It seems that my heater, air conditioning, and all of my HVAC is stuck in defrost mode. No air coming out of my vents that face me but all of it coming out of the windshield vents. What few searches I did indicates that I may have a vacuum leak. I checked all of the vacum lines in the engine compartment and all that I could find is a couple of elbows that lead to my PCV valve have collapsed and also one up near my throttle body. Could this be the problem? I changed the one on the back of the intake last year because it couldn't handle the oil vapors. I just can't get over the fact that as long as vacuum lines have been on vehicles Ford still can't make one that will last. Anyway if these collapsed elbows are the problem what do I ask for at my Ford Part's Counter. If I don't go prepared and if it's not easily found on their microfilm they will tell me that I need to just have my engine replaced if you know what I mean.

 

Oh yeah, it's a 98 F150 with the 5.4L

 

my friend had a 99 that he couldn't control where the a/c came out you know turn a corner and defrost and then turn the other way then feet.... so on. it ended up being the actuators that move the flaps, they were broken. seems he brought it to a shop that had done a few of these. problem is they have to remove your whole dash $$$$ it is fix and while they were in there he change the evaporator core cheap and hooked up a ground wire to help on the electrolosis.(seems to be a problem i had to change mine also) see if that helps

 

You need to trace the vacuum lines that go to the controls. A loss of vacuum will set the system to defrost. Pull the bazel that surronds the radio/heater controls
and then remove the screws that hold the controls in. Pull them out and test the lines for a leak.

Regards

Jean Marc Chartier

 

Did you look behing the battery?

 

Just ask for the PCV hose assembly. Its around $25. It comes with the elbows and the hard lines as a kit. We replace them a few times a week. All rubber will eventually deteriorate with oil.

 

How hard is it to change the PCV hose assembly? Looks like it goes under some other hoses and behind the throttle body.

Thanks

 

Those elbows were a free recall at my local Ford parts counter. Mine all collapsed on my 97 F150 4.2v6. Check recall web site from f150online