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Old 12-31-2011, 04:02 PM   #61
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Anybody ever have trouble with getting the defrost/heat/vent lever to vent? My defrost and heat works perfectly but the lever wont go to vent(if i force it the cable clip at the lever pops out). I also tried moving the lever by hand and it just wont go. Is there a spot where something gets hung up? Any idea on where to start looking?

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Old 12-31-2011, 05:13 PM   #62
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Quote:
Originally Posted by 88irocz View Post
Anybody ever have trouble with getting the defrost/heat/vent lever to vent? My defrost and heat works perfectly but the lever wont go to vent(if i force it the cable clip at the lever pops out). I also tried moving the lever by hand and it just wont go. Is there a spot where something gets hung up? Any idea on where to start looking?
Mine is like that because I closed the drives side gate by hand because it wouldn't close any other way.

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Old 12-31-2011, 06:05 PM   #63
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Mine is like that because I closed the drives side gate by hand because it wouldn't close any other way.
hmm maybe the PO did that..Thanks ill check it out
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Old 12-31-2011, 09:57 PM   #64
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I replaced the 'cowl grill' with a piece of Lexan (plastic) to block it off from the outside completely! I had to cut a big hole in the Intake duct (behind the glove box) so it now re-circulates The 'Cabin-Air' for more efficient heating! Who needs a vent in a JEEP? (and here in so.dakota it does get down to 30- 40 BELOW most winters!) note: I have a piece of screen over the duct 'Hole' to keep 'crap' out of the heater core.
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Old 12-31-2011, 11:20 PM   #65
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Here we are months later and my heater works so well that i often have to turn it off during my drive lol. Now if only we had a way to direct the air flow to our hands...
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Old 01-01-2012, 02:27 PM   #66
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Anybody ever have trouble with getting the defrost/heat/vent lever to vent? My defrost and heat works perfectly but the lever wont go to vent(if i force it the cable clip at the lever pops out). I also tried moving the lever by hand and it just wont go. Is there a spot where something gets hung up? Any idea on where to start looking?
So after taking a look i realized there is more then one cable controlling the defrost/heat/vent. one went right above the floor heat vent which only has 2 positions (moves for defrost and heat) then when you move the lever to vent another cable opens the floor vent (passenger side). Im sure there is more going on but thats all i know. Turns out the cable going above the heat vent just needed some length adjustment.
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Old 01-01-2012, 03:53 PM   #67
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This is a great write-up. Someone want to do a step by step on how to completely remove the heating system from a YJ? My heater core is leaking, I don't run the heat anyway (as there's no top or doors) and the Jeep only gets driven on nice days. Would be nice to remove it to simplify things.
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Old 01-01-2012, 07:29 PM   #68
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Wranglerhaven,

This is the best "write up" I have ever seen on this topic, and truly most other topics. Thank you for the effort and the commitment to getting it done so other jeepers can learn and do. Thank you.

Yesterday, I have just removed my heater core assembly and it took me about 30 minutes tops. Putting it back was another 30 minutes.

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Old 01-27-2012, 11:34 AM   #69
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so good write up, but i have a question, how "loud" is the heater when on low. because i cant hear/feel any air but when i put it on high its like an airplane. Is this situation normal?
The heater should sound about like that, although I do notice some air on low. Mine is pretty loud on high though.

This write up is fantastic. I found that my vent door was just stuck open but my blower was working fine. Thanks a lot!!
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Old 01-28-2012, 11:19 AM   #70
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This was the BEST!!!!
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Old 01-29-2012, 01:27 AM   #71
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'denisbaldwin' Here's some info for ya...

Your heater fan motor assembly bolts to the rear of your heater box. You gotta pull everything that gets in the way first like the glove box ! But there is alot of LITTLE nuts, bolts and cable clips (don't break these!) that have to come out first to completely remove the heaterbox out of the jeep! (and it's big! goes from your gaspedal to the passenger side of the tub!) Hint...I removed the passenger seat too! for more working room.
This also means a few nuts on the 'firewall' of the engine compartment near the rear of the 6 cylinder valve cover and battery box....and heater hoses also ofcoarse This is doable, it's just a job that requires lots ofm patient and care! and a few well placed cuss-words! REMEMBER TO REMOVE THE HEATER DUCT HOSES for your defroster AND the 'motor' wire connecter' CAREFULLY! When you pull ( ie:YANK) the 'box' off the inside firewall it will be awkward and heavy. Remember you are also pulling it straight back to clear the back of the motor out of the firewall! (take your time it'll take ya full day the first time you do this job...so do it right) And just so your prepared...its more of a 'pain' aligning the bolts putting it back! (don't forget a new piece of insulation foam pad 'doughnut' around the new motor assembly after you have it re-installed on the box.....otherwise you will get a water/air leak into your jeep!) Note: if you are doing the 'blazer upgrade' you might have to 'run' a new ground wire from a blower motor mount bolt, to the plug for your motor wires (make sure you 'test' this plug and wireing BEFORE you mount the new motor to the box...it'll be a crying shame to go thru this job and have it not work!) GOOD LUCK, you will be proud of yourself when it's done!
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Old 02-13-2012, 01:52 PM   #72
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Excellent Post

I have my heat box debugged down to the defrost/heat selector...the cable is fine so I detached it but I can't get the selector lever that moves the internal door to move ..it seems jammed solid ... any advice?

I was trying to figure out how to remove the floor duct so I could see up in and determine whats wrong.

Does anyone happen to know where I can find some actual photos of that internal door assembly??

Thanks
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Old 02-20-2012, 07:13 AM   #73
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Heater and Engine performance??????

Ok this is totally aggravating me. My 1993 Yj 2.5 lt jerks and runs rough unless my heater is on then it runs fine. I have tested this quite a few times and every time I turn the heater off my engine will jerk/stumble when I get down to 30mph and then as I am increasing speed and passing 30-45. I have asked mechanics at my hobby shop and they don't have a clue. Any Ideas??????

It has normal leaks here and there It does not use oil. It could use a new exhaust system. I got the distributor cap wet awhile back and I took it off on a couple of days ago cleaned it out and buffed the prongs in it.

WTH,
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Old 02-21-2012, 09:22 AM   #74
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Ok When You 'turn the heater on'...The only thing I can think of is this: There is a Vacume switch that works with your 'heater control'...I would Trace the 'Vacume Line' that comes out of your Fire-wall into the Engine Compartment and Dis-connect it from the manifold vacume source. (plug the nipple on the manifold that you took the hose off) And see if ya still have the problem. Honestly I can't think of any other thing that would "Tie the Two Together" Let us know what You Find !!
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Old 02-21-2012, 04:55 PM   #75
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Yea it has got me confused. Could it have anything to do with the alternator?
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Old 03-17-2012, 06:24 AM   #76
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I changed the MAP sensor still no change.
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Old 03-24-2012, 03:12 AM   #77
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Pulling Vacuum Lines

Quote:
Originally Posted by jerreyjeep View Post
Ok When You 'turn the heater on'...The only thing I can think of is this: There is a Vacume switch that works with your 'heater control'...I would Trace the 'Vacume Line' that comes out of your Fire-wall into the Engine Compartment and Dis-connect it from the manifold vacume source. (plug the nipple on the manifold that you took the hose off) And see if ya still have the problem. Honestly I can't think of any other thing that would "Tie the Two Together" Let us know what You Find !!
Ok so i started pulling vacuum lines that go into the manifold and the idle on my jeep went up and it sounded better.
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Old 04-12-2012, 07:02 PM   #78
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94 yj wrangler se 4.0L heat flow from defrost: heater off

I have a 1994 jeep wrangler YJ SE 4.0L I have hot air flowing through my defrosts vents even though I have all the sliders moved all the way to the left.

Is this a failure of the vacuum motor, or is the blend door partially open and not closed, or all the above?

the swing door for defrost to floor vents closes no problem there.

Thanks for this excellent write up on the heating system in the YJ. I had hoped that someone would have posted the hot defrost air flow I am experiencing, but no one did.

Any advice will be greatly appreciated!

Thanks

Hot in Houston and Getting Hotter! lol
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Old 04-12-2012, 09:35 PM   #79
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Ok so i started pulling vacuum lines that go into the manifold and the idle on my jeep went up and it sounded better.
you re looking for the tiny line that splits with the cruise control vacuum. that is where mine is
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Old 04-12-2012, 09:36 PM   #80
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Originally Posted by scorpn View Post
I have a 1994 jeep wrangler YJ SE 4.0L I have hot air flowing through my defrosts vents even though I have all the sliders moved all the way to the left.

Is this a failure of the vacuum motor, or is the blend door partially open and not closed, or all the above?

the swing door for defrost to floor vents closes no problem there.

Thanks for this excellent write up on the heating system in the YJ. I had hoped that someone would have posted the hot defrost air flow I am experiencing, but no one did.

Any advice will be greatly appreciated!

Thanks

Hot in Houston and Getting Hotter! lol
mine does it too. mine is the cables is not working so during the summer i have to lay under and move everything closed by hand
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Old 04-30-2012, 03:57 PM   #81
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Problem Continues

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Originally Posted by jerreyjeep View Post
Ok When You 'turn the heater on'...The only thing I can think of is this: There is a Vacume switch that works with your 'heater control'...I would Trace the 'Vacume Line' that comes out of your Fire-wall into the Engine Compartment and Dis-connect it from the manifold vacume source. (plug the nipple on the manifold that you took the hose off) And see if ya still have the problem. Honestly I can't think of any other thing that would "Tie the Two Together" Let us know what You Find !!
Ok Changed the Map, Distributor Cap, Plug's and Wires, Fuel Pump went bad changed it, Fuel Filter, could the Fuel pressure regulator have anything to do with this I noticed a vacume line that runs into the back of that only thing that i could think of is that when the heater is on it pulls enough of a vacume that it opens up that regulator properly.
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Old 04-30-2012, 09:55 PM   #82
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Funny thing is I am currently re-installing the complete dash assembly, the wiring has kinda got me stumped, neither the shop manual nor the parts book break down the interior wiring harness attachments." trial and error may have to do". the cable connections for the heating/vent components had me a little confused until I found this post.
thanks alot!!
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Old 05-01-2012, 04:40 PM   #83
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wrangler defroster system

I see no one has asked about the heat / defroster system for some time. 2 questions come to mind. First- where is the right side cowl vacuum motor located?? Second, for some time my heater and defroster blow a very small amount of hot air. What I just noticed is that as I drive over the hill I commute over each day that when I have my foot into it keeping up speed I get a great increase in volumn of air thru my defroster. Once I top the hill and get back to cruising the volumn of air falls off again. If it were the vacuum motor acting up I would expect it to fall off when I have my foot into the gas pedal. Not the other way around. I really appreciated the diagrams of the heat / defrost system, they were great. Thanks
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Old 05-04-2012, 10:15 AM   #84
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A question for you about the heater. Your diagrams helped a bunch to understand my system on the 87 wrangler. I converted it to the 94 fuel injected from one of the catalogues and I love the differance it made in the drive ability of the vehicle. Now I have a problem with the heater. I don't seem to be able to get the vaccum I need to operate the vacuum motor. There are a couple of places in my work commute that I have my foot into the throtte pretty good and I get lots of air from my defroster at that point. However when just easy cruising I lose the air flow. I have tried differant ports on my manifold but the problem stays the same. When pulling hard I get good air flow, when cruising I have minimum air flow from the heater or defroster. At a loss as to where to look now. Any thoughts on the subject. My brakes work fine, the motor runs very well, its not like I am missing vacuum all over, its just my heating system. Your thoughts would be appreciated. Darrel
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Old 05-26-2012, 07:15 PM   #85
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Im not sure how to put pics on here but i think i put it on here as an attachment hopefully it works
Im not sure if you got this answered yet, but my 93 yj has the same set up. The pins were for the AC controls, one ran the temperature the other was the fan speed for the vents just under your Heat/def/vent control. It has its own fan and of course condenserr. The Switches... one controls the rear window wiper and water spray if you had a hard top. Possibly the other was for the defroster on the rear window. Mine only has the wiper and only one switch there. It has the hole for the 2nd switch but when I aquired the jeep it was already removed. I hope this is not redundant.
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Old 09-21-2012, 11:07 AM   #86
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Great post!! Thanks for all the info.
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Old 01-01-2013, 02:33 PM   #87
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More heating (and another question)

The diagram and explanation helped extremely. I lost heat a couple weeks ago and am trying to work on it on my own. I am a so-so mechanic, but paying for a rebuilt trans limits my options.

I replaced the thermostat and have had no luck. What should I be diagnosing next? The hoses leading to the heater coil do not seem to get hot or even warm. Is the thermostat malfunctioning again? Do I look for a clog?

Also I found something disconnected cable that I cannot identify, but suspect may be related. Sharing an electrical connection with the thermostat housing was this from the attached pics...

Any help would be greatly appreciated.

BTW it is a 95 Wrangler YJ (no AC option installed)
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Old 01-25-2013, 12:42 PM   #88
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you guys are talking about another vent that is behind the speedo under the dash... i have a 95 with A/C installed... would i be able to see it with the A/C unit under the dash or do i need to pull the speedo out to see it?
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Old 01-26-2013, 01:38 PM   #89
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I have hot water going to and from my heater core, but no heat.
The blender door feels like it opens and closes all the way but I'd like to take a look at it to make sure.
What's the best way to get to it?
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Old 03-28-2013, 08:37 AM   #90
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this is a great post! On other board there was a way to give someone a rep for doing a good deed... so consider yourself repp'd.

I just got my jeep home tuesday only to find her taking a leak in my driveway! it's cool tho, I see where it's coming from. It's the top hose to the heater core behind the dash. I haven't had a chance to really get into her yet but I'm hoping that it's only the hose and there isn't a crack or anything on the nub sticking out of the firewall. Anyone ever see anything like that? I'm also going to need to check the blower motor.. I hit the switch and it does nothing. Having this diagram is really helpful.

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