Does anyone have a GOOD diagram of how the whole vent/heater system works and which cable goes where and how they interact? Some of my levers don't do anything no matter which knob pull and I'm trying to figure out what I need to do to fix it, the FSM is horrible on the diagrams. Many of the cables work not only one lever, but also have a rod or another cable going to another lever across the dash and I can't find a good diagram to explain how all these work and interact with each other.
Heater/Vent system and cables diagram
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SouthernGypsy
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Usually there is a ?Flap? attached to the end of the tube to let water out but keep everything else out.
If there is air trapped in the heater then the heater core never gets hot. But you say the core is hot. So it cant be that
Only other thing that can let cold air in is the blend door inside the heater not closing all the way.
I assume you already checked the other two fresh air ducts and cowl seal.
Are your window hinges bent? sometimes if you don't lube your hinges and try to fold your window down, it bends the hinge and then the seal doesn't seal properly.
Also make sure the AC hoses are sealed were they pass through the firewall. The one I pulled out just had a clay like sealer.
It's amazing how so little of hole can let in so much cold air.
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If the damper to the driver side "crotch vent" is not closing, it will allow fresh air from the cowl intake to dump under the dash without passing through the heater core.
It's possible that the lever may not be moving (it is connected via a control rod to the combination lever near the glove box). Or if the lever is working, it's possible the damper itself may be damaged or blocked by leaves or something.
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James,
I know you said the cold air is coming from behind the dash, but....
Are the floor drain holes plugged. If not, they could be contributing to the problem.
Matt
I know you said the cold air is coming from behind the dash, but....
Are the floor drain holes plugged. If not, they could be contributing to the problem.
Matt
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Neither of our Jeeps have that flapper valve on the end.What?
it looks like this:
![Image]()
Rubber tube with a flapper valve on the end.
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John,
Obviously we can't see it but when we work the temp knob we can hear the blend door closing and opening. It makes a distinctive thud as it hits each direction if you move the slider fully from one extreme to the other quickly enough.
The drivers side vent is closed, I also was able today during the day to look inside the cowl and can see a flapper door at the drivers end which is closing and opening as she moves knobs inside.
The cowl seal? That maybe what we need to check, how is the cowl sealed to the box that's inside of it. Where ever the fresh air is coming in is coming in seems to be very high up in the very center of the dash.
I can say that we have never gotten any water inside like some people complain about. Had to pick her up from work last week during severe flash flooding, driving rain so intense that at times everyone on the road just had to stop because we couldn't even see the road, if I'd had a hood ornament I wouldn't have even been able to see it. Yet never got a drop inside the Jeep. So at least I know everything in that situation is sealed enough and drains must be functioning properly.
Obviously we can't see it but when we work the temp knob we can hear the blend door closing and opening. It makes a distinctive thud as it hits each direction if you move the slider fully from one extreme to the other quickly enough.
The drivers side vent is closed, I also was able today during the day to look inside the cowl and can see a flapper door at the drivers end which is closing and opening as she moves knobs inside.
The cowl seal? That maybe what we need to check, how is the cowl sealed to the box that's inside of it. Where ever the fresh air is coming in is coming in seems to be very high up in the very center of the dash.
I can say that we have never gotten any water inside like some people complain about. Had to pick her up from work last week during severe flash flooding, driving rain so intense that at times everyone on the road just had to stop because we couldn't even see the road, if I'd had a hood ornament I wouldn't have even been able to see it. Yet never got a drop inside the Jeep. So at least I know everything in that situation is sealed enough and drains must be functioning properly.
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Yep, one of the first things I did with both CJ's was to take rubber plugs we have assorted sizes of in our shops bins and find and plug every single hole in the firewall or floorboard that was not being used. The Laredo had a few, the Limited actually didn't have any except the two small screw sized holes where I removed the sensors when I did the nutter-bypass and when I did that I put the screws back in so I wouldn't have even those small holes.
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One diagnostic attempt would be to seal the cowl vent temporarily and see if the problem stops. Then you have narrowed it down to either something in the heating system, or air getting in elsewhere.
^^This^^
I'd take the vent grill off and stuff a towel in the box and take a drive with all the controls off to see if there is any air getting in.
I'm still thinking it's a problem with one or more of the damper doors or controls because you were able to resolve the problem once by messing with the controls. Seems like a leaking gasket or seal to the cowl would not be affected by anything you did to the levers/cables.
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Haha, thanks, actually I did it easier than that. I just took duct tape and taped over the stainless cowl vent cover all except a very tiny strip in the middle (I was afraid to block it 100%) and went to the grocery store and back... Heat! Lots of heat.
Yes but that's when I had a bad cable to my temp-selector which I replaced the Tuesday morning when it arrived.
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What position does the big drain hose from the cowl belong in from the factory?
Both of ours angle inwards kinda toward the center (though one more than the other) but that means that water draining from the cowl might possible splash right down onto the starter if it was raining hard enough and that doesn't seem quite right unless there was a reason for it.
Both of ours angle inwards kinda toward the center (though one more than the other) but that means that water draining from the cowl might possible splash right down onto the starter if it was raining hard enough and that doesn't seem quite right unless there was a reason for it.
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After tinkering with it in the shop I have a hypothosis but I need someone to confirm if it's possible... Keep in mind mine has an A/C unit under the dash so seeing up under there is a major pain.
I took the grill off the top of the cowl and the box seems to be in good condition, the flapper door on the end seems to be in good condition and closing fully, but the box seems to move around just a little.
What holds the box tight against the bottom of the cowl? My theory is that whatever is supposed to hold it has either loosened and allowing a gap (couldn't get my finger in to verify) between the top of the box all around and the underside of the cowl which is allowing air to flow out all around the gap by-passing the flapper, OR, there was once some kind of weather stripping around the edges which has deteriorated over time and is allowing air past when your going fast down the road.
Is that a possibility?
Not knowing how the box connects and seals to the underside of the cowl it's just an idea at this point. A dozen web searches and I have yet to find any pictures showing this particular spot and how it connects and seals.
I took the grill off the top of the cowl and the box seems to be in good condition, the flapper door on the end seems to be in good condition and closing fully, but the box seems to move around just a little.
What holds the box tight against the bottom of the cowl? My theory is that whatever is supposed to hold it has either loosened and allowing a gap (couldn't get my finger in to verify) between the top of the box all around and the underside of the cowl which is allowing air to flow out all around the gap by-passing the flapper, OR, there was once some kind of weather stripping around the edges which has deteriorated over time and is allowing air past when your going fast down the road.
Is that a possibility?
Not knowing how the box connects and seals to the underside of the cowl it's just an idea at this point. A dozen web searches and I have yet to find any pictures showing this particular spot and how it connects and seals.
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James,
There is suppose to be a gasket between the heater box and the cowl vent.
And, since I know what your next question will be, I don't think they are available any more. You may have to make your own.
Matt
There is suppose to be a gasket between the heater box and the cowl vent.
And, since I know what your next question will be, I don't think they are available any more. You may have to make your own.
Matt
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Thanks, that's what I needed.
Probably a good thing I picked up two rolls of self-adhesive weather stripping at Walmart yesterday. Duck brand 3/4" wide x 1/2" wide x 10' long and a 3/8" wide x 3/16" thick x 30' long. Both were $3.99 (they sell it in about 8 different sizes) and I figured they might come in handy.
I'd actually intended to lift the top slightly and run the wider strip along the underside of the hardtop where it meets the window frame, I bought an new gasket for there already online that said it was for that spot but it was a joke and we are still also getting some air in up there as well at interstate speeds. I had a small amount around the house already but only about 8 inches left, which I took a couple of weeks ago and stuck it so it was overlapping itself so I had 2 double wide 4" pieces, and I used a small flat tip screwdriver to tuck them up into the front corner on either side where you always seem to get that gap just above the upper front edge of the door no matter how well you align the top. Worked great. I think someone had suggested filling that area with silicone every year but I was thinking what a pain that would be to clean out between each year and the gap may not always be perfectly the same each year, but this will just fall out on it's own when the top is lifted off. Even drove through all 8 cycles on the ultra deluxe mode on a touch-less drive-thru car wash on our way out of town on Christmas and never got a drop of water inside the Jeep.
_
Probably a good thing I picked up two rolls of self-adhesive weather stripping at Walmart yesterday. Duck brand 3/4" wide x 1/2" wide x 10' long and a 3/8" wide x 3/16" thick x 30' long. Both were $3.99 (they sell it in about 8 different sizes) and I figured they might come in handy.
I'd actually intended to lift the top slightly and run the wider strip along the underside of the hardtop where it meets the window frame, I bought an new gasket for there already online that said it was for that spot but it was a joke and we are still also getting some air in up there as well at interstate speeds. I had a small amount around the house already but only about 8 inches left, which I took a couple of weeks ago and stuck it so it was overlapping itself so I had 2 double wide 4" pieces, and I used a small flat tip screwdriver to tuck them up into the front corner on either side where you always seem to get that gap just above the upper front edge of the door no matter how well you align the top. Worked great. I think someone had suggested filling that area with silicone every year but I was thinking what a pain that would be to clean out between each year and the gap may not always be perfectly the same each year, but this will just fall out on it's own when the top is lifted off. Even drove through all 8 cycles on the ultra deluxe mode on a touch-less drive-thru car wash on our way out of town on Christmas and never got a drop of water inside the Jeep.
_
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Great thread, I would like to jump in here. So it's -35 here in Toronto, and the heat in my '86 CJ is barely warm. So I looked under the dash and made sure that the Air/Temp control on the far left is working, and it seems to be fine.
So, I haven't tried to adjust the Off-Heat-Vent control by hand underneath like in this thread here yet:
http://www.jeepforum.com/forum/f8/problem-my-air-control-mechanism-1069506/
If the above control is not working correctly, would that cause the heat to be not hot and just barely warm?
Thanks for all youz guyz help.
So, I haven't tried to adjust the Off-Heat-Vent control by hand underneath like in this thread here yet:
http://www.jeepforum.com/forum/f8/problem-my-air-control-mechanism-1069506/
If the above control is not working correctly, would that cause the heat to be not hot and just barely warm?
Thanks for all youz guyz help.
This may be a stupid question but how do the cables hook up to the brackets? The end of the cable is like a tiny key ring and the bracket only has a small hole on it. Do I have the remove the whole cable assembly from the dash to attach the end of the cable? Am I missing an easy trick here?
In the picture early in this post by SoutherGypsy, there is a cable with an adjustment knob located near the passenger fresh air intake (sorry, can't figure out how to insert pictures). I am looking at all the typical places to purchase on, but I can't tell if I order the whole cable kit if it will be in there. It looks as though only the cables from the control knobs to the units are included. Could someone please let me know if that is there understanding also. Also, if anyone knows where I could find one, it would be greatly appreciated.
Thanks,
Brad
Thanks,
Brad
That cable with the adjuster on it is not available anywhere as far as I've been able to find (not as part of a kit or individually).
If anyone has found a source for it, I'm sure a lot of people would be interested!
Mine is held together with Bandaids and bubble gum (okay, I used epoxy, but you get the idea).
If anyone has found a source for it, I'm sure a lot of people would be interested!
Mine is held together with Bandaids and bubble gum (okay, I used epoxy, but you get the idea).
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I just manually adjust the flap that cable goes to. I need a new one also
The brackets holes are slots and the plastic ring on the end of the housing can be pulled out of the bracket and then the end of the cable can be slipped off.
The brackets holes are slots and the plastic ring on the end of the housing can be pulled out of the bracket and then the end of the cable can be slipped off.
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