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Low air flow on both driver and passenger side vents

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8.2K views 32 replies 5 participants last post by  55555Jeep  
#1 ·
Hi everyone, first time jeep owner here. Purchased a 2004 WJ SE V6 last year. I'm having some airflow problems with a manual controlled system that I can't seem to find a cause for. When searching, it seems various folks are having similar issues but nothing seems to completely resolve it? Some of their issues did not seem to involve or list the same things I've checked. I have low airflow on both the driver and passenger side vents. Center vents has what I feel is good air flow. Cold air feels coldish, hot air is hot air. Here is what I've done, checked so far.

Checked for codes and no codes are present. I simply get the word "Done."

For fan speed, low does not work. The other three settings work accordingly. The high or max speed feels and sounds like a jet engine out the center vents, but not so much on the driver/passenger side. As I select a slower speed, airflow does come out all the vents, but center vents are the strongest. Even on the lowest speed that does work, the center vents are the strongest and driver/passenger side are still weaker.

Pulled blower motor out. It spins in the right direction. While the motor was out, I did confirm that the lowest speed does not turn on the blower. When on high, the blower motor is definitely pushing air.

Check recirculation door and it moves appropriately when selecting different settings.

Just by happenstance, one morning the heat stopped working recently when trying to figure this all out. It was a bad actuator. When I pulled it off, I checked the spindle for the blend doors. It moves and stops accordingly. I turned on the heater and manually rolled the spindle. I could hear the door as it closed on the opposite side. I started getting hot out the vents. Just like with the AC, center vents have a lot of hot air blowing out. The driver/passenger side vents does not have the same level of flow coming out. I replaced the actuator and it made no difference in airflow.

Pulled the cowl off to see if there was any blockage anywhere and I don't see anything. There is no cabin air filter.

When the air is running, there is a very slight air flow coming out the floor vents. With a wet finger, you have to be right at the mouth of it. An inch away and you don't feel anything. There is no other air flow felt under the dash area.

Recently took several long road trips. Unless the weather is in the 80's or lower, the AC does not really cool down the back seat area. The last road trip, I ended up having to install a behind-the-seat dual fan setup just to get some air circulation in the back.

The only other idea I had was to drop an endoscope down the vents to see if there is anything affecting things. Other than the low air flow on the driver/passenger side and everything else works accordingly, I can't imagine there being any type of vacuum hose problem. In addition, I can't imagine that with the blower motor not working on low but normal for the other settings would affect things to the extent that it does.

Is this the dreaded low vent issues plaguing the WJs like many others here are having problems with or is there something else I can try?
 
#4 ·
I have some more air now. It better but not quite there yet. From another post here... and I can't post links yet.

I got behind the AC control panel. The foam around the evaporator box was loose and I had air escaping. Not a lot but noticeable. Took out as much foam as I could and sealed the gaps with some foil HVAC tape. The airflow to the driver and passenger side vents was a bit better. I noticed that the foam the seals the center vents only had indentations on 3 sides and not four. I'm thinking that perhaps the foam there was not lined up properly. I am going to pick up some window stripping to make a better seal to see if that helps. Again from the above-mentioned post, I cut out a little bit of the opening behind the glove box. Afterwards, I drove down to get a frosty and while doing so, the air felt a lot better. After all of this, it does suggest that mechanically, everything is sound, I just have gaps from aging, deteriorated foam.

I have a blower motor resistor on order and should be here within a few days.

My current living situation does not allow me to pull the dash apart, but it does make me wonder though. If I pull off the cover I taped down, would it be possible to reach up inside and make a seal from the gaps from the deteriorated foam? It would obviously be slow going and using maybe 2-4" inches of HVAC tape at a time.
 
#5 ·
So long time update. Still having a weaker air flow on the driver side and passenger side vents. Center vents seems to be working okay. During the hot summer, even on high, it is not enough to cool things down in a timely manner. Here is what is working. I get hot and cold air when the respective temperature is selected. Hot air and cold air goes out to the other various vents when selected such as the floor and defroster. Going back to the main cabin vents, after replacing the blower resister, I got all the speed settings. For the driver and passenger vents, even with the weaker air flow, you can still feel the difference in speed settings.

As previously mentioned, I replaced the resistor and I have also replaced the blower motor. I cut a hole above the blower motor and can see the door moving accordingly. I tried switched the wiring polarity on the blower to rule out being opposite. The blower was wired correctly in the beginning. I noticed a substantial drop in air flow when it was reversed.

I took the dashboard off today to to try replacing the foam seal with weather stripping. https:// w w w . jeepforum . com/forum/f310/how-get-plenty-air-your-dash-vents-3544698/ There was some gaps missing in the foam but not enough that I would think would cause the problems. I cleaned out all of the foam and replaced it with the weather stripping from the link. Much to my frustration, that did not fix the airflow to any real satisfaction. I checked the vacuum lines and I am not seeing anything broken, cracked or disconnected.

Since I am getting hot/cold going out to the other vents when selected, I am thinking that I can rule out doors not being a problem? More so since no codes are present when checking. My next step is to run an endoscope through the driver and passenger side vents to rule out obstruction.

Any thoughts?
 
#10 ·
Indeed, it does take time and patience. I did remove the tape and reapply it later during the heater core replacement. The box that the duct in your pics is attached to has come completely out of the vehicle. The various air and temp control door live inside of it, along with the heater core and the a/c evaporator. I spent most of a Saturday and much of Sunday doing it all, but that included a lot of cleaning while I had it all apart. Last I saw, a shop will do it for you for around $1,100. The heater core cost me $42 and the weatherstrip that I used cost around $20, IIRC. :)
 
#11 ·
Love it!!! Truly amazing job what you did. I wish more people with the same problem find this post because I was going crazy. Hopefully this spring I get enough nerve to take apart the dash. Around me I don’t think I could ever find a mechanic to do what you did with such patience. I would happily do the work just nervous about putting it back together as well. But again not guts no glory. Many thanks again!
 
#25 ·
It will help to have a helper when it comes time to get the dashboard out of the vehicle. It's quite awkward to get it out alone. :( Other than that, take your time, be patient, take lots of notes/pictures, bag and tag all of the bolts and nuts. It would probably be helpful to have a laptop with you, with that YouTube video from Brians Mobile One queued up. He goes through every single thing that you'll need to touch to get it all apart.
 
#26 ·
Well Harry I am getting closer. Changed out the ac evap and heater core. I am having a issue lining up the bottom aluminum ac line under the hood the top one went in. And now to put back the dash ouch. It’s not lining up easy at all. I saw another video where they come in at a 45. I tried that but wow this thing is heavy and awkward.
 

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#28 ·
So now you now why I said that it's good to have a helper. ;) The dash is huge and awkward to move around by yourself. I did mine a few years ago, so I don't recall many details. :(

As for that small tube, IIRC, that's what freezes your toes if you wear sandals while driving with the a/c on in the summer. :oops:
 
#31 ·
I am getting warmer…. Have a small white connector cannot find for the life of me where it goes. I marked everything…maybe a spare…. It driving me crazy. and one screw under the steering wheel to the right did not line up for me. :-(.
 

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