Air vent problems

[tweeve]

The problem I am having is that all the AC, Heat and all air that comes from the vents inside my XJ all come though the winsheild vent. No matter what I do it just come though the winsheild vent. It hasnt been a problem untill now because it just now started getting really HOT 95+ by mid morning. (I live in the desert) At times When I first trun on the AC it starts from the normal vents but then quickly changes to the window vent.

Anyone know how to fix this. Its getting too hot here to just run the AC out of the window vent.

 

[old_man]

99% of the time this is caused by a vacuum leak in the engine compartment. On the Renix units, it most commonly found on a hard line running behind the battery to the vacuum bottle mounted on the passenger side back of the bumper.

 

[cykaaro]

Did you have the unit out/unplugged at all?
Strange thing happened with my '90. I was doing some rewiring, so had the unit unplugged. When I put it back in, regardless of position, the air was only coming out from the windsheild. Turned off the truck, waited a bit, then turned it on, and all was well again.
I'd say old_man would know far better than me, but just something that happened I found and thought I'd put it out there.

 

[tweeve]

Did you have the unit out/unplugged at all?
Strange thing happened with my '90. I was doing some rewiring, so had the unit unplugged. When I put it back in, regardless of position, the air was only coming out from the windsheild. Turned off the truck, waited a bit, then turned it on, and all was well again.
I'd say old_man would know far better than me, but just something that happened I found and thought I'd put it out there.

no I havent had the unit unpluged. I bought the XJ this way. I was in April and I really didnt need much AC back then and figured I could get it fixed by the time it got too hot. Well its hot out now and I didnt get it fixed.

OldMan, I check the vac line didnt really see anything wrong with it. Had the engine running and all the connections seemed to alright. It does suck in air so I know that is atleast working. Any other Ideas.

 

[AZ Jeff]

Vacuum leak. Common problem on older XJ's, especially with the vacuum line that runs from the reservoir tank in the right front bumper, and passes under the battery box. Batter acid eats the line up, and creates a vacuum leak.

 

[tweeve]

The vacuum line look ok... I held my finder over the line before and after the connections and there was a vacuum. Could it be the tank?

 

[AZ Jeff]

That's possible. Plug the line going to the tank for a few mnutes and see if the vent system works as designed.

 

[tweeve]

Pluged the line with my finger, No change. I did find out though that its just not the windsheild, its stuck on bi-level. So its still on the windsheild and the floor now.

 

[Darky]

I'm having the same problem and my cruise control just quit as well, around the same time. I never put the two together until reading this but the cruise is run by a vacuum as well. Could it possibly have something to do with the cruise control module?

 

[tweeve]

I'm having the same problem and my cruise control just quit as well, around the same time. I never put the two together until reading this but the cruise is run by a vacuum as well. Could it possibly have something to do with the cruise control module?

I dont have cruse contol

 

[Eagle]

Any other Ideas.

It IS a vacuum leak -- you just haven't found it yet. The climate control vents are vacuum actuated, and they default to the defrost position when vacuum is lost. You just have to trace all the vacuum lines until you find the one that's not doing its job.

 

[BruteXJ]

Eagle, do you know offhand where one would start looking for vacuum leaks doing this on a '99 Sport?

Mine just started doing this off and on about a month ago.

 

[dakotus]

WAIT
youre saying its coming from the dash vents then it stops then starts coming out of the window vent?

During that transition, can you hear a sort of flap shutting? Its a little door to the airbox behind the radio. It directs air up to the window, or out to the dash vents.

let me know if you can hear that, and we can move forward...

 

[tweeve]

WAIT
youre saying its coming from the dash vents then it stops then starts coming out of the window vent?

During that transition, can you hear a sort of flap shutting? Its a little door to the airbox behind the radio. It directs air up to the window, or out to the dash vents.

let me know if you can hear that, and we can move forward...

Yes When they do switch you can here. something change like a flap or gate moving.

 

[rstarch345]

dakotus is on the right track, but I'll bet its the selector switch mounted on the dash. It's vacuum operated and if the seal in it dries out or becomes loose, sometimes it works, sometimes it doesn't. If your tight on cash, you might try the JY otherwise, a factory unit would be best.

 

[dakotus]

take a look at some of these threads...

http://www.naxja.org/forum/showthread.php?t=19909&highlight=defrost+vent

http://www.naxja.org/forum/showthread.php?t=19185&highlight=defrost+vent

Yea I have this problem as well. Its not the switch. Its the little actuator arm coming from the vacuum motor. There is a star/hex shaped gear that sits inside the airbox. That gear is connected to the actuator arm. The actuator arm is connected to the vacuum motor.

that's a super quick sketch of it.


Now what happens: That star/hex shaped gear has a tendency to pull out of the tube that its in. When that happens it cant grip the gear inside and thus the vent door has no resistance on it, and it shuts. It only shuts on a higher fan setting because there is more air pressing against the door. I've noticed with mine, sometimes it will even close at setting 2, and obviously everything higher.

Some others have suggested that you bend the actuator arm toward the passenger side, thus moving the gear back in its holder. Another suggested to me, to pull the gear out, and put some superglue on it, then jam it back in there.

You really need to take out the radio and part of the speedometer dash trim to see whats going on. Perhaps you can find a better solution.

For all this knowledge I have one request..... If you find a solution that works for you other than what i posted, please share it with the community here. There are too many threads that go unanswered.

phew!

Nik

 

[tweeve]

thanks I'll look into that...but first Im going to poor over the vacuum lines. I only was able to get a quick look at them yesterday. If its not a vacuum problem with the lines, it loo like im going to have to tear into my dash...I'll keep you guys posted.

 

[tweeve]

ITS FIXED!!!!

It was a vacuum line problem. Old Man was right.

There is a little dohicky (I dont know what is it) at the right of the drivers feet that two vacuum lines plug into one of those got unpluged. Pluged it back in started the engine and truned on the AC everything seems to be working now. I was about to tear into the Air box like dakotus was suggesting when I saw that vacuum line. Thank god it was a vacuum line. I really didnt want to tear into the air box.

 

[dakotus]

Tweeve
Good stuff! :thumbsup:

can you post a picture of what you are talking about. I would like to fix mine tonight as well. Im more than willing to try this than to try my own suggestion!

 

[schmiedel]

Hi,

Avoiding to start another thread, I'll use this one because it seems the closest to my question.

I'm having exactly the same problem, and I have found the vacuum line leading to the reservoir beneath the front bumper, but I can't find no reservoir.

Now my question is, what should I troubleshoot in order to solve the whole problem appropiately?