Heater Control problem.

[Silver91XJ]

Ok i just got a 91 Xj about 6 months ago and the vents dont work at all. the defrost works but non of the other vents. What can i do to fix this? can i just swap out the heater controls or is there a flap stuck in the heater piping itself?

[JLANE99XJ]

I think your second thought is correct, mine does a sticking thing sometimes where there's a delay before the direction of the vent air is sent to where the control is selected, almost then it makes a flapp-noise & all of a sudden then like magic the air comes out where its supposed to.


no clue as to how to fix it, since mines not completely broke yet, I suggested looking @ a Haynes Manual on the parts brakedown of the vent system & go from there....

[Silver91XJ]

Ok thanks, where can i get one of these books. I'm pretty mechanically sound, i have been working on my cars for a while now, but i just got into jeeps so any help in the right direction would be appriciated. :)

[jdogg4]

I would think it was the second one aswell. When you switch it over does the defrost sound like it's being redirected and it's just not. my old better of an S-10 did that and the flap tap were the cable conected to snapped off. so it would close the defrost but wouldent open the vent air path.

[Silver91XJ]

It acutally doesnt make any noise at all when i switch from vent to defrost. i guess i follow the cable and see if its broken. Thanks guys. :D

[jdogg4]

It acutally doesnt make any noise at all when i switch from vent to defrost. i guess i follow the cable and see if its broken. Thanks guys. :D

So do you hear the fan going when it's in defrost but not when it goes to vent? it used to right?

[Silver91XJ]

Yes it used to turn on but doesnt any more. And yes the fan comes on when its on defrost.

[jdogg4]

check that cable first see how that is. If it's not coming on when switching it over it might be o heck I don't know at this point. I just replaced my flap that was broke and it worked.

[XJRay]

More than likely you have a vacuum leak. On the Cherokees, the default position is the defrost (if there if no vacuum pressure). Start by looking for cracks in the vacuum canister (located behind the passenger side bumper). Then trace the line back to the firewall, looking for cracks. Do you have cruise control (if it is a vacuum problem, it would probably affect the cruise control as well)?

[jdogg4]

More than likely you have a vacuum leak. On the Cherokees, the default position is the defrost (if there if no vacuum pressure). Start by looking for cracks in the vacuum canister (located behind the passenger side bumper). Then trace the line back to the firewall, looking for cracks. Do you have cruise control (if it is a vacuum problem, it would probably affect the cruise control as well)?


GOD I feel like a dumb @$$ I totaly spaced that one out. XJRay U da man

[Silver91XJ]

More than likely you have a vacuum leak. On the Cherokees, the default position is the defrost (if there if no vacuum pressure). Start by looking for cracks in the vacuum canister (located behind the passenger side bumper). Then trace the line back to the firewall, looking for cracks. Do you have cruise control (if it is a vacuum problem, it would probably affect the cruise control as well)?


Yeah the cruise control doesnt work either. Thanks man i really apriciate it. It it just normal vacumm line?

[gvltiger]

i was having the same problem with my vents as well. I followed the vacuum hose from the front of my xj and found it broken in two. my vacuum line was plastic and simply snapped. I haven't replaced yet with a new line, but duct tape works wonders in creating a vacuum. This is only a temporary fix, but I now have heat and air blowing out of my dash.

[deadpedal]

More than likely you have a vacuum leak. On the Cherokees, the default position is the defrost (if there if no vacuum pressure). Start by looking for cracks in the vacuum canister (located behind the passenger side bumper). Then trace the line back to the firewall, looking for cracks. Do you have cruise control (if it is a vacuum problem, it would probably affect the cruise control as well)?

Vacuum leaks suck. They are easy to diagnose sometimes, but hard to track down and fix. I was about to guess the flaps too. I wouldn't feel too bad about it, but then again... I'm almost legally retarded.

[JLANE99XJ]

silver91xj --
Ok thanks, where can i get one of these books. I'm pretty mechanically sound, i have been working on my cars for a while now, but i just got into jeeps so any help in the right direction would be appriciated. you can get a haynes manual at just about any auto-parts chain store like advanced auto parts or pep boys, they're full of trouble shooting info & give pretty desriptive breadowns on maintence & repairs, it'll be the $8 or so you spend for your xj.

xjray-- thanks alot man (your info helped me also) as i said my vent selection hasn't been working like it should either, and now that you mention it my cruise isn't quite like it was 10k miles ago, it has been letting the vehicle slow down on hills & i have to gas it to keep it up to the set speed, unlike before i had a fender bender & my front end was reworked by a body shop, i'll bet something is loose in my vacum system also. thanks again... :)

[Silver91XJ]

Ok i found that the vacumm line was diconnected at the canister under the bumper and my vents worked for about 10 min, but i think theres another leak that i cant find. where can i order new lines?

[deadpedal]

You probably won't have to order lines. Just go down to Advance Auto, Napa, AutoZone, etc. They should have your sizes of vaccum lines in stock, they're pretty available and shouldn't cost you very much, like
$4-$6 bucks for the lines you need.

The problem you need to fix is to locate exactly where the leak is at, trust me, easier said than done. This way, you can be sure that you are actually fixing the problem, instead of simply replacing all of the vacuum lines.

[Silver91XJ]

I had time this weekend to actually look and listen to all my vacuum lines and there are no leaks in them at all, how ever i did find out the where the lines go into the back of the heater core that some air was blowing out of the firewall. so now im thinking that i line has either broken there or come off its connection. How hard is it to drop the heater core?

[thejeepingoat]

oooooo its phun......

[Silver91XJ]

[Quote]oooooo its phun......[Quote]

LOL, does that mean you wouldnt recomend someone to do it on there own? :D

[thejeepingoat]

no no, i just had a lot of phun doing it......bc i was just tearing it out to tear it out....an old rusted out cj5 with no top, doors or completes floor panels for that matter didnt exactly have use for a heater. If you are going to keep the heater, I would be carefull taking off the input/output hoses that connect to the input/output on the firewall,they are probably cooked on there pretty good and you can break the input/output lines. A good trick it to take a box cutter and slice the hoses lengthwise along the where the fittings are. Be gentle and careful if you want to keep your heater, if not.........have phun :g

[jdogg4]

I have yet to do it on a jeep but when I did it on one of my old chevy's O man That was a pain in the rear. I was able to do it but it just was a pain to get to and took forever. You know there are some projects that are hard but yet you still had a good time doing it. Well lets just say I didn't have fun with this project.