Black Air Vent Vacuum line... blockage??

[Sedition]

Hi all,

My air vents are stuck on "defrost" mode no matter what the selector is set to.

So I need some advice reguarding the thin hard plastic vacuum line that runs from the "ball accumulator" into the fire wall and then on to the airvent actuator.

It appears that there is a blockage in the line somewhere between the connector on the outside of the firewall and the connector on the inside of the fire wall. Is this normal? say from a valve somewhere that I haven't seen yet or is this the blockage that is causing my vents to stay on "defrost" mode?

It's hot as hell out here during the day and I really miss the air con blowing ice out of the vents. Any advice in reguards to this no matter how trivial it may be would be greatly appreciated.

I Thank you in advance, Luke...

 

[FIND]

A blockage would be odd to see since nothing really gets in there. I would assume there was a leak if anything or that the actuator is bad.

 

[Sedition]

I can't suck or blow air through that certain piece of vacuum line with both ends open even with shop air.

 

[FIND]

Wow, that's crazy. Is there a check valve on that portion? You should be fine for that section to replace it with rubber vacuum hose.

 

[bobflood]

As I understand it, "defrost" is the default position if vacuum fails. Sure sounds like something is blocking the vacuum connection. Can you bypass that line with a temp connection just to verify?

 

[Sedition]

Thanks for the input guys, When the stores open again after good friday, Ill pick up a long length of that vacuum line or something similar to bypass and hopefully varify this particular peice of line running through the fire wall is indeed the problem.

 

[Turdle]

http://www.explorerforum.com/forums/showthread.php?t=192842&highlight=defrost+delete

Hope this helps

It could be a "melted" line along the fender well. Might have contacted the exhaust manifold.

 

[Sedition]

Right hand drive

Just to clear things up a little...

On the right hand drive models the vacuum lines are as follows in the diagram below. The vacuum lines start on the same side as the American models then cross over to the other side of the engine bay via the back of the engine, along with the heater hoses.

I have a blockage in the black vacuum line between the blue arrows on the diagram. I think the vacuum line may be kinked or damaged in some way in under the airconditioning equipment preventing vacuum continuity through the firewall.

It looks as though I may have to remove the heat shielding and disassemble some of the plastic air con housing to replace this line once I have confirmed that it is this line that has caused my issue.

Now my question is to you, Do the left hand drive models also have their vacuum lines running through air con equipment before entering the firewall? and if so how much of this equipment, if any, must be removed to replace this line?

 

[Turdle]

Yup, that is the area which could get hot. I have a tip--secure the front end up on a jack stand, and, remove the inner fender liner and tire. This will allow you to see thru the wheel well into that area. The lines actually go below the HVAC blower housing into a bulkhead connector pictured in the thread I linked in my previous post.

 

[Sedition]

Wow, that's crazy. Is there a check valve on that portion? You should be fine for that section to replace it with rubber vacuum hose.

I'm not sure if there is a check valve in that section or not. I'm going to have a poke around now and try to find some type of rubber hose to bypass it, for confirmation.

 

[Sedition]

Thanks for the advice Turdle.. I definately believe I will be going in from underneath the wheel well once confirmed..

 

[Sedition]

Mission complete, sort of...

Well I checked and confirmed the piece of vacuum line that I suspected to be blocked. In the end I decided to use an air compressor hose that plugged directly into the source and ran down under to the passenger side footwell plugging into the black line with the aid of a piece of blue tac.

I turned the key, the engine started and idled like crap for about 30 seconds. once all the air was vacated from the air compressor hose the Idle smoothed out and I had air con from my vents, confirming the suspected section of vaccuum line was stopped up. Hell yes, now time to take off the passenger side wheel and arch aprons to reveal the culprit.

Two jacks are better than one when you don't have jack stands, I really should get a pair of jackstands from Super Cheap Auto one day.

Removing the apron and guard were a piece of cake. The suspect vacuum lines were found between some insulation and the plastic air con box, upper middle of above pic, I decided to discard the air con insulation as it was only getting muddy in there. It's amazing how mud seems to get everywhere in these things when you offroad them.

The offending section of hose. I pulled on the black vaccuum hose a little and it snapped in two, I could then only blow through one piece of the snapped vacuum line prooving that one side was indeed kinked closed.

After repairing the vaccuum line with some aquarium tubing, seelant and cable ties I then set to work putting my truck back together and road testing my Air con vents.

Well the Good news is the vents now work but the problem is when I step on the gas they go back to defrost mode then once I get up to speed they work again. Dam it must have particially pulled a vacuum line out of the ball accumulator whilst I was looking for a line to tap into. Oh well thats this afternoons job.

 

[cnsheets]

Make sure the tubing you are using for the repair is not collapsing due to the vacuum. This could close off the line just like your previous problem.

 

[Turdle]

^^^ especially as it warms up. it gets real mushy

 

[bobflood]

Make sure the tubing you are using for the repair is not collapsing due to the vacuum. This could close off the line just like your previous problem.

In fact, that is why they use hard plastic line instead of aquarium tubing.

 

[cnsheets]

I had a similar problem on a hard line, it rubbed on the AC dryer and developed a hole. I just cut the damaged section out and made sure that both ends were straight and would meet up flush, then used some RC airplane fuel tubing to splice the two together, but I made sure the hard line touched each other inside the rubber line, this way there was no way it could collapse. Its been 2 years since I did this fix without problems.