Eagle Posted February 1, 2009 Share Posted February 1, 2009 I have a problem with my 2000 XJ Sport that I need some guidance with. On a long trip last week, I noticed that when I have the heater controls set to blow through the outlets on the front of the dashboard, the two center outlets (the ones just above the radio) don't blow the same. The one on the driver's side will blow warm or hot air, and at a pretty forceful velocity if I have the fan up to anything besides the slow setting. But the outlet just beside it will be blowing cold or much cooler air, and at substantially less volume and/or velocity. I would have thought those two outlets would be fed from a common duct, but that's apparently not correct. Have any of you encountered this? Got any idea how difficult it might be to try to correct it? It has to get fixed -- this explains why my wife is never happy with where I have the heat set -- in order to send heat her way, I have to crank it up far enough that I get baked. Link to comment Share on other sites More sharing options...
Pete M Posted February 1, 2009 Share Posted February 1, 2009 I'm not entirely familiar with the inner workings of the Jeep HVAC system, but maybe a blend door is stuck? How does the ductwork separate cold AC air from the heater core air? (meaning if you had the AC on but didn't want it at max, how does it regulate what comes out the vents?) Link to comment Share on other sites More sharing options...
Eagle Posted February 1, 2009 Author Share Posted February 1, 2009 I'm not sure. The late model XJs have a slightly more complex/civilized HVAC system than the early ones. I wasn't running a/c, just trying to get heat out of the face-level outlets rather than the under-dash outlets. I *THINK* the temperature is controlled by varying the blend of outside air and the amount of air from the heater core. But I'm not sure. But what has me baffled is why one half of the two center outlets (which look like they are in the same housing) has heat and the other one doesn't. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 1, 2009 Share Posted February 1, 2009 I had one of the flexible hoses that run from the center plenum to the dash discharge vent partially come off one time (think I did it myself when I was doing something up under the dash). It caused very reduced air flow out of that vent. Link to comment Share on other sites More sharing options...
BLHTAZ Posted February 1, 2009 Share Posted February 1, 2009 This picture is from the Chrysler parts look up as I still have access right now ;) . It is not great, but it appears that the center vents are fed directly off of the housing by a door that may not be opening, while the outers are fed by those flexible hoses... Don't know if this will help, but it's all I could find. Link to comment Share on other sites More sharing options...
Eagle Posted February 1, 2009 Author Share Posted February 1, 2009 Thanks, Taz. That makes perfect sense ... but it doesn't explain how one of the two center vents blows lots of warm/hot air, and the other blows less/colder air. I guess I need to look inside with a bright flashlight and see who/what's living in there. The FSM suggests that I can just pop the vent drums out of the face of the dash -- any verification that a fumble-fingers like me could actually do that without trashing the part AND the dashboard? Link to comment Share on other sites More sharing options...
BLHTAZ Posted February 1, 2009 Share Posted February 1, 2009 Thanks, Taz. That makes perfect sense ... but it doesn't explain how one of the two center vents blows lots of warm/hot air, and the other blows less/colder air. I guess I need to look inside with a bright flashlight and see who/what's living in there. The FSM suggests that I can just pop the vent drums out of the face of the dash -- any verification that a fumble-fingers like me could actually do that without trashing the part AND the dashboard? I knew the picture wasn't going to hold the answers...just hoping that it could help you get closer. The parts pics are always very generic. It would seem, by looking at that pic, that there would be only one door going to both of those vents...therefore it would not be possible for one to blow different than the other. Being that you have that situation, I think the picture is very deceiving and is not really what you have in there. I know that the vent louver assemblies can be removed, as I have sold them before, but I have no clue how unfortunately. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted February 1, 2009 Share Posted February 1, 2009 if one or both of your outer vent tubes fell off, the warm air would tend to blow from where they connect to the HVAC more than through the center vents, because there is less restriction down there. if that's the case, perhaps you're getting hot air out of one side because of vacuum pressure differing side to side or something like that. just make sure everything is connected properly, I'd think that should fix it... Link to comment Share on other sites More sharing options...
aemsee Posted February 1, 2009 Share Posted February 1, 2009 Since this box is not a dual zone box this is a puzzler. How is the heat at the vent on her far side? As jeepco said, it could be due to the outer tube being off acounting for the reduce air flow. But not those flex hoses. I believe that they are just for the demisters and only flow air in defrost mode. If you look at Brents picture you can see that they hook on at the defrost plenum, not the main box. There are hard plastice channels that are hooked to the back side of the dash to go out there. (IIRC?)The air goes in the box, throught the evap coil then through the heater core. The blend door positions itself to control whether no air, all the air or just some goes through the heater core to be heated. Hence the term "blend air system". The blend door is vertical in the box, and the door for the dash vents is horizontal. I cannot recall if there are baffles in between the two like a dual zone system has. If there is you could have something in the box restricting hot air just affecting the one passage. Link to comment Share on other sites More sharing options...
Sir Sam Posted February 1, 2009 Share Posted February 1, 2009 Thanks, Taz. That makes perfect sense ... but it doesn't explain how one of the two center vents blows lots of warm/hot air, and the other blows less/colder air. I guess I need to look inside with a bright flashlight and see who/what's living in there. The FSM suggests that I can just pop the vent drums out of the face of the dash -- any verification that a fumble-fingers like me could actually do that without trashing the part AND the dashboard? Yes they just pop out, but don't remove them that way. Instead remove the whole bezel. Put the shifter in 1st/2nd(or whatever gear it decided to pick) and then grab the radio bezel and pull back, it just pulls off, if its never been off before it might take a little force. Once this is off you can actually access the vent behind the "shutters" Link to comment Share on other sites More sharing options...
aemsee Posted February 1, 2009 Share Posted February 1, 2009 :agree: Link to comment Share on other sites More sharing options...
Eagle Posted February 1, 2009 Author Share Posted February 1, 2009 Yes they just pop out, but don't remove them that way. Instead remove the whole bezel. Put the shifter in 1st/2nd(or whatever gear it decided to pick) and then grab the radio bezel and pull back, it just pulls off, if its never been off before it might take a little force. Once this is off you can actually access the vent behind the "shutters" So the vent drums come out with the bezel? Excellent -- if I don't trash the bezel. Mine's a 5-speed, so I assume you want me to put it in 2nd or 4th. Where do I pull to have the bezel come off intact rather than in small pieces? Top? Bottom? Sides? Pull up like it's hinged at the top, or straight out? Link to comment Share on other sites More sharing options...
Sir Sam Posted February 1, 2009 Share Posted February 1, 2009 Yes they just pop out, but don't remove them that way. Instead remove the whole bezel. Put the shifter in 1st/2nd(or whatever gear it decided to pick) and then grab the radio bezel and pull back, it just pulls off, if its never been off before it might take a little force. Once this is off you can actually access the vent behind the "shutters" So the vent drums come out with the bezel? Excellent -- if I don't trash the bezel. Mine's a 5-speed, so I assume you want me to put it in 2nd or 4th. Where do I pull to have the bezel come off intact rather than in small pieces? Top? Bottom? Sides? Pull up like it's hinged at the top, or straight out? Strait out, just grab it where you can and pull it back out. You actually don't need to move the shifter, but it does help. Link to comment Share on other sites More sharing options...
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