Open Ended Vacuum Hose

[Hoppy]

Gents,

I am presently troubleshooting P0171 and P0174 codes on my 2000 Explorer SOHC. While chasing vacuum leaks I came across a vacuum hose on the right side that is not connected to anything. The hose leads to the relay box underneath the air filter box, is grey in colour and I cannot find a hook up for it. I plugged it with a screw for the time being. It looks as though it comes from under the evaporator/blower housing.
One thing I noticed, when driving down the freeway with the air on Max AC and i accelerate to go up hills or to get up to speed, the Max AC servo must dump its vacuum and goes to normal air until I let off of the pedal.
I am not sure if these two are related, but I would appreciate your help. I am trying to figure out what is wrong prior to changing my pre-cat O2 sensors.
Thanks,
Hoppy.

 

[vroomzoomboom]

that vacuum line, if i am correct should lead to a "valve" that sits beside your heater box. it opens and closes depending if your a/c is running. it looks like this

http://www.explorerforum.com/forums/showpost.php?p=2615053&postcount=8

its called a heater control valve.

 

[Hoppy]

Nope, It is tied into a wiring harness going to the MAF sensor. It was found under the intake air box, under a relay box where the fog lamp relay is located. The photo you show is not from a SOHC, or at least not a 2000 SOHC.

 

[Turdle]

Yes, the other end runs down under the air box to the vacuum reservoir ball.

While this thread is for another problem, ( which I bet you are experiencing), follow it for a diagrams and pictures to help you understand.

Hope this helps you.
http://www.explorerforum.com/forums/showthread.php?t=192842&highlight=defrost+vacuum+globe

 

[Hoppy]

Thanks Turdle, I will go and see if I can find this globe. The line that was dangling near the relay box was grey in colour.

I will post my finding.

 

[koda2000]

well, that vacuum hose has to connect somewhere, but on a different note, plugging a vacuum hose with a screw (especially these tiny hoses) doesn't work very well as the air get sucked in around the threads. when i first got my xlt the A/C would switch to the defrost vents every time i went up a hill. i knew i had a vacuum leak somewhere. upon examination i found someone had put a screw in an unused port on a t-fitting. i removed the screw and t-fitting and replaced it with a piece of hose. problem solved.

 

[Hoppy]

Turns out the hose went to the coolant diverter valve under the alternator. Tried the servo and it worked. Plugged in the line to it, had to cut the end of the hose off, but started the truck and it worked. Vacuum was applied in off and Max AC. I took the air box out, moved the relay box out of the way and took a photo of the globe as I could not see it from above. All was well there. I will see if my codes keep coming back, it usually takes about a week or two for them to show up.

Thanks for the help and advise.

Hoppy