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Old 02-19-2008, 10:36 AM   #1
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AC & Heater Won't Blow Through Dash Vents

I am a newbie who had an issue with my '97 TJ 4 cylinder Wrangler's HVAC system not blowing through the dash vents. It would blow through the floor and defrost at any temperature I wanted but it just wouldn't come out the face vents. I don't know a whole lot about cars but I couldn't find a simple, detailed fix for my problem so I thought I’d create one for other beginners. From my reading, I gather that this forum is oriented more toward the advanced Jeepers so I apologize for the simplistic nature of this post. If any of you pros read this and spot any erroneous info, please correct me.

When I bought my '97, the guy said the AC issue just started happening and his mechanic friend said it was a broken selector switch and it would be cheap to fix. After extensive research on Wrangler forums, i figured it was probably an issue with the blend door and not the selector. The blend door controls the flow of air from defrost vent, dash vent, floor vents, etc and not the blend of hot and cold air like I originally assumed. I called my local dealer and he confirmed that it sounded like a broken blend door and it'd be $95 to hook it up to the computer and another several hundred dollars to repair if the blend door was indeed the culprit.

The blend door and actuators are located behind the dashboard. If you're looking at the dash, they're to the left of the AC selector switch and down about 6 inches. You can see them if you stick your head in the floorboard and look up underneath the dash. I removed the plastic knee blocker piece under the steering wheel and the metal piece beneath that so i could get some more light.



I had seen other posts where guys laid upside down in the driver's seat with their heads in the floor so I tried that for about an hour and almost killed myself. I couldn't fit my arms under the dash so I ended up taking out the driver's seat and I highly recommend going that route. I was intimidated by this prospect at first but it's simple. Mine just had 4 bolts connecting it to the body. Then I had to remove the seatbelt sensor wire from the seat which is just a little plastic clip by the seatbelt which comes right off. Once I was finally able to maneuver, I located the problem.

If you look under the dash, the blend door and actuators are a few inches up and to the left (if you're lying upside down). I believe the actuators or diaphragms are 3 round silver ball looking things with silver arms coming out of them. They look like the picture below:

The arms attach to the blend door and this is where my problem was. The plastic part that connected the silver arm to the blend door had broken and it was very hard to get my hands into that little area. If you have the AC on and move the vent selector between the various positions, you will see the arms move and you can see what position gives you the most access to the area. I found the broken arm and reattached it by getting a 1 inch #10 sheet metal screw from Home Depot. I put it though the hole in the arm and screwed it back in without even worrying about taking the original broken piece out of the blend door because it's hollow anyway. here's what the broken piece looks like and where I reattached it I think the blend door for the dash vents was the middle of the 3 actuators. I ended up having to hold the plastic door attachment piece in place with my left hand and taking the screwdriver in my right hand through the removed knee blocker I referenced earlier.

I apologize for the long, tedious post but hope some other newbs can get some use out of it.

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Old 02-19-2008, 12:34 PM   #2
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Good information to have. I have a 97 as well, but haven't had the issue. Good to know that somebody can fix this w/o having to go through major problems.

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Old 02-21-2008, 07:39 PM   #3
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I also have a 97 and am having the same problem. Except the problem with mine is that the air is not coming out of the windshield defrost vent. I haven't tore apart the dash yet to examine it but it sounds like we have the same problem.
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Old 02-21-2008, 08:10 PM   #4
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Just so you know before you rip your dash apart, check the vaccume lines. My 97 had the same problem and last weekend, I looked under the hood, and there was a long vacuume line that came unplugged from the intake manifold
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Old 02-22-2008, 12:19 PM   #5
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hey Superbad, are you able to switch between floor, dash, etc.? if you can get all the other vents to work except the defrost, i would imagine it's the blend door but if you're stuck in one vent position and can't cycle between the others, you may have a vaccume leak. SB5551 mentioned above to check your vaccume line and it's worth a shot before tearing out the dash. if there's a serious vac leak though, i believe the HVAC defaults to defrost position for safety reasons so it wouldn't make sense not to get defrost. sounds like a broken blend door. you might also want to check for air flow obstructions if you find out it's not the blend door. good luck.
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Old 02-22-2008, 03:51 PM   #6
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I was thinking it was the door also but I hadn't had a chance to check it out yet. I'm getting air out out the dash vents and the floor but none out of the defrost. Hopefully this weekend I will have a chance to look at it.
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Old 02-22-2008, 05:55 PM   #7
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well my 97 has the exact same problem as superbad007 and i think its the same problem but it's 2 freaking cold out to mess with it now gotta wait till spring! or a good 50 degree day and that sux because i have no defrost
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Old 02-23-2008, 10:40 AM   #8
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Solo, if you need defrost for safety reasons, you may consider disconecting a vac line from the HVAC. I think defrost is the default mode if the line comes off. You wouldn't have the other vents but at least you'd be able to see. I don't know how easy the lines are to get off and on though. If you consider this though, you may want to consult someone on here who knows more than me. Just thought i'd throw that out there.
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Old 07-25-2008, 07:27 PM   #9
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Is it possible to find a diagram of the HVAC system to follow the vacum lines.
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Old 07-25-2008, 07:40 PM   #10
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Quote:
Originally Posted by Gonemudding View Post
Is it possible to find a diagram of the HVAC system to follow the vacum lines.
Yes..... If you get a FSM...full service manual.

If you still have questions pm me.
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Old 07-27-2008, 10:47 AM   #11
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Where would you find an "FSM" Im not very happy with the Haynes manual.

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Old 07-27-2008, 11:28 AM   #12
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Funny, I had this same exact problem but it was vacumm hose that had come loose under the hood (though I thought it was switch). When the hose was back in place the vents worked fine.
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Old 08-11-2008, 02:10 PM   #13
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my problem is that i don't know where the hose starts from. or what an intake manifold is or looks like. anyone have pics? it's hot here in california and i need my AC to cool me not mu windshield!
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Old 08-11-2008, 03:53 PM   #14
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I just fixed mine on friday or saturday, removed the drivers side kick knee panel, looked to see which blend door arm was broken, snapped out the vac motor for the broken blend door, took off the broken arm attached to the vacum motor, took it inside, big hole to little hole in the broken arm, must be part of the forming process, dropped a big enough self tapping screw down [phillips head brass which is all I had for the size and length] then screwed it thru the broken part. That left about an inch sticking out of the end of the arm. Now the hard part, you need to see where the fully retracted and fully extended postions of the vac motor are, once you figure that out you just stick the broken arm back in the hole with the screw sticking out, start screwing it in, the door shaft already has a hole in it the same size as the broken lever part then screw it in till it's tight, don't strip it or you will need a bigger screw. Unsnap the vac motor and put it back on the end of the lever, snap the motor back in and thats it.
The vac motors are on bayonet fittings they pull straight away and push back in. If I have to do it again I'll stop by a hobby shop and pick up some cycoanlite [sp?] plastic super glue made specifically for plastics and use that one the threads exercising extreme caution not to get it on the sides of the lever or you will make that lever a permanent part of the heater box.
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Old 01-09-2009, 06:25 PM   #15
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I have a similar problem with a 2002 jeep Wrangler every thing works except that the AC or heat only blows to the defrost position. I tried to get inside to see what is going on but I was not able to open it completely. I could touch the nob selector in the back and from it there is a power cable and another cable (6 color small pipes, not actual wires) which goes to the dash, the floor and the defrost actuators. Not sure how the nob switch works as it is not mechanical, maybe they work with air preasure. The 6 small pipes split behind the globe box and I can disconnect this bundle and the air still goes only to defrost position. If I disconnect the power for the switch still all the air goes to the defrost position. By reading the forums some people is saying that it could be a problem with the VAC or the blend doors. On the 2002 I think the problem is the switch itself but not sure so any help is greatly appreaciated.
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Old 01-09-2009, 06:59 PM   #16
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Ok so if what I call the deflector flap(deflects the air from floor,vents,and defrost)is really a blend door and what I call a blend door that opens and closes to change from hot and cold air Or can be opened half way to blend for warm air (located on the passenger side) Is called what????
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Old 01-10-2009, 11:20 AM   #17
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I also have a similar problem, much like the one above. No matter which position is set, except Off, the air blows through the Defrost. I have looked around a little but I am not really sure what to look for. Does anyone have any pointers or can lead me in the right direction? I am no mechanic but I would much rather do it myself than pay someone a lot of money to do it for me.

Thanks!
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Old 01-10-2009, 09:30 PM   #18
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Quote:
Originally Posted by superbad007 View Post
I also have a 97 and am having the same problem. Except the problem with mine is that the air is not coming out of the windshield defrost vent. I haven't tore apart the dash yet to examine it but it sounds like we have the same problem.
I have the same problem with no air going to the defrost vents. I did find the actuator arm broken that controls that part of the system. I removed the broken arm and paid a dealer to order me a new one, but after several months, he finally said he couldn't get the part! Does anyone have the answer on ordering a replace actuator arm for the defrost. Seems it should be simple. *(This is for my 1997 Wrangler 4 cylinder) Thanks!
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Old 01-05-2010, 04:36 PM   #19
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I'm new to this forum but you people are great. Very knowledgable. All my heat and AC went to my defroster vents and all I could imagine was crawling under the dash to find the problem. This post said to check under the hood and I found the vacuum line just hanging around and doing nothing. Found where to plug it in and Wa La the problem was fixed. The rubber boot was loose on the fitting so a small ziptie tightened it up nicely. Thank you all for the info. It took ten minutes to fix. can't get any better than that.
Thank You again
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Old 01-05-2010, 05:58 PM   #20
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I had this problem and me and my dad just replaced some hose and it worked perfect again, not sure which hose it was though.
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Old 01-21-2010, 01:19 AM   #21
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missing pictures

I don't suppose we could get a repost of the pictures to go along with the original post?

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Old 02-01-2010, 03:22 PM   #22
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I thought the A/C vacuum selector switch was bad because all selections resulted in air only from the defrost & floorboard. Plus the knob turned funny like the switch was just broken. All vacuum lines appeared to be in good shape and connected. I bought a replacement switch online ($25 with shipping). Went to replace it this weekend and after pulling the dash and controls, realized nothing was wrong with the switch, the knob was cracked where it engaged over the switch and was slipping when turned. I turned the switch with pliers and everything worked fine. Replacement knob ordered for $12. I'll keep the replacement switch in case the old one DOES go out (like I really would be able to find the replacement by then)
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Old 02-01-2010, 04:42 PM   #23
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I have an '02 Wrangler and had the same problem. I crawled up under the dash to look for broken door hinges and found nothing. I zip tied vacuum lines to manifolds and nothing. I found a cracked vacuum hose in the fender on the passenger side under the battery. FIXED! So nice to have heat that blows through the vents all the time!

Check here: http://www.wranglerforum.com/f5/heat...ors-37712.html
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Old 02-01-2010, 05:29 PM   #24
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Anyway to get the pictures back up?
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Old 02-01-2010, 07:55 PM   #25
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Great job with the pics. I did the same thing to my defrost about a month or so ago. Sheet metal screw worked great. When I hit the defrost now, the door slams open. As soon as I did it and it worked, I thought "I wish I would have taken better pics". I think this little tip can save a lot of people some headaches.
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Old 02-01-2010, 08:35 PM   #26
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Having sort of the same problem, I don't understand how to get to the blend door, i've looked all over and all I see is a big vacuum can opening a big flapper door and a lever that moves with the temp slide adjuster. Both are located on the passenger side, under the dash. I looked under the steering column, behind the cover, but didn't see anything. I followed the vacuum line from the intake manifold back to the "T", then traced it both ways. It seems to be plugged in tight, but I may replace it all to be sure. I'm getting very frustrated with my TJ, its the first Jeep i've had since high school. It has to be vacuum related, because I can't seem to direct the heat where I want it. I was surfing ebay for other parts and came accross something called a "heater treater". The pics and description made the fix look simple, but what is under my dash doesn't look like the pictures.
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Old 02-02-2010, 07:02 AM   #27
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Great job with the pics. I did the same thing to my defrost about a month or so ago. Sheet metal screw worked great. When I hit the defrost now, the door slams open. As soon as I did it and it worked, I thought "I wish I would have taken better pics". I think this little tip can save a lot of people some headaches.
Where did you find the pics?

Thanks
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Old 02-02-2010, 03:30 PM   #28
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PM sent, thanks.
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Old 04-08-2010, 09:50 AM   #29
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I just fixed mine on friday or saturday, removed the drivers side kick knee panel, looked to see which blend door arm was broken, snapped out the vac motor for the broken blend door, took off the broken arm attached to the vacum motor, took it inside, big hole to little hole in the broken arm, must be part of the forming process, dropped a big enough self tapping screw down [phillips head brass which is all I had for the size and length] then screwed it thru the broken part. That left about an inch sticking out of the end of the arm. Now the hard part, you need to see where the fully retracted and fully extended postions of the vac motor are, once you figure that out you just stick the broken arm back in the hole with the screw sticking out, start screwing it in, the door shaft already has a hole in it the same size as the broken lever part then screw it in till it's tight, don't strip it or you will need a bigger screw. Unsnap the vac motor and put it back on the end of the lever, snap the motor back in and thats it.
The vac motors are on bayonet fittings they pull straight away and push back in. If I have to do it again I'll stop by a hobby shop and pick up some cycoanlite [sp?] plastic super glue made specifically for plastics and use that one the threads exercising extreme caution not to get it on the sides of the lever or you will make that lever a permanent part of the heater box.
How long did it take you to do the fix and is it still working?
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Old 04-08-2010, 09:51 AM   #30
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Originally Posted by firemanfrmny View Post
I have a 97 TJ and have the full service manual for it in PDF format, if anyone needs it
Got the email for the manual.

Thanks a million!!!

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