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Searched but couldn't find another instance of this.
2004 E500 quad-zone climate:
Front zones appear to work correctly, and I am getting the infamous squeaky fan problem. But, the rear vents, regardless of settings, get zero airflow to them. In the winter, you can feel just a tiny bit of warmth emanating from them, but no real air flow. Opposite in the summer...you can feel cold emanating but no airflow. The lower armrest warms and cools as expected.
Another anomaly is at some point while driving, I'll hear what sounds like a flap closing behind the passenger's side of the dashboard. When it closes, it has no affect on airflow, or anything for that matter. Just thought it might be worth a mention.
It would be nice to have the car diagnosed and flaps controlled to find out which flap makes the sound you have observed. Actually the 4-zone control unit should have a diagnosis mode, I cannot remember how one gets into the control mode and how flaps are controlled but instructions should be found from the forum (I assume it is the same as the W210 and similar control units even if they look completely different).
Have your tried switching the charcoal filter on and off? Any sounds from that.
Could it be that the rear centre nozzles are not supposed to blow hot air like the centre front nozzles do not (at automatic settings)?
It would be nice to have the car diagnosed and flaps controlled to find out which flap makes the sound you have observed. Actually the 4-zone control unit should have a diagnosis mode, I cannot remember how one gets into the control mode and how flaps are controlled but instructions should be found from the forum (I assume it is the same as the W210 and similar control units even if they look completely different).
Have your tried switching the charcoal filter on and off? Any sounds from that.
Could it be that the rear centre nozzles are not supposed to blow hot air like the centre front nozzles do not (at automatic settings)?
I'm not sure the flap sound is really a symptom of the problem, I just thought it noteworthy.
Yep, tried with the charcoal off/on. I've tried pretty much every combination of settings. I used to just be able to set it on auto and feel air coming out of the vents, in the summer time at least. Don't remember checking in prior winters to be honest. But it should at least blow cold air, if that's the setting. That's not happening either.
Did you check the airflow adjustment wheels? Of course you did. Stored fault code will identify if left and/or right rear air flap actuator motors M16/30 & 31 are malfunctioning (BTW A32m2 is blower motor). If isolated to center vents you may also want to check rear air nozzle let me know if you need removal instructions.
Did you check the airflow adjustment wheels? Of course you did. Stored fault code will identify if left and/or right rear air flap actuator motors M16/30 & 31 are malfunctioning (BTW A32m2 is blower motor). If isolated to center vents you may also want to check rear air nozzle let me know if you need removal instructions.
C'mon D.....give me a little credit.
I'll hook up my scanner to it tonight and see what's what. Is it correct to assume that the left and/or right flap actuator motor(s) controls it's correlating center and b-pillar nozzles? Meaning, does the right flap motor control air to both the rear right and rear b-piller nozzles? And the left one controls it's left rear and center nozzles?
I think I forgot to mention that the rear b-pillar vents are not passing air either.
It's hard to believe that both would be bad at the exact same time, no?
But, when I manually adjusted the temp to HI, air direction to main/face vents and fan to highest position, airflow wasn't very hard out of main vents either. It was blowing decent, but not on par with the sound of the blower motor, if that makes any sense. Sounded like the blower motor was working it's tail off, but the air just wasn't making it through the system.
I removed the cover underneath the glove box, where the charcoal filters live, and I could see the flap that opens and allows air towards the charcoal filter. It was open. And stayed open, regardless if I selected the charcoal filter button on the selector panel. So, it appears air is always flowing through the filters. Shouldn't make that much of a difference, or so I thought. I attempted to pop out the charcoal filters to see if that made a difference. I had to use all of my might to get the filters to pull down and out. It appears, that they had bloated inside of their housing. Now is a good time to mention that I replaced these last summer with a non-oem set. Once I got them out, and put the covers and lower panel back together, I could feel increased airflow to the b-pillar vents. Still not blowing hard, but harder.
Then I started debugging the airflow controls. It appears, that even when you're not in auto-mode, the system still uses some sort of logic to decide where the airflow should go, based on temperature selected, and maybe even outside temp. If I set the temp to hi-heat, and selected face level output, the b-pillar and rear vents still blew harder than before, but still soft overall. If I selected a temp closer to LO/COLD, the airflow increased in the rear registers. Once I locked it at the LO/COLD temp, all 4of the rear vents shutoff. All of this while auto was turned off, and the selector was at face level output.
So, it looks like I have a problem where the system is always diverting airflow towards the charcoal filters no matter what. Maybe my bloated non-oem charcoal filters where dampening the airflow egress.
Does a document exist that can educate me on the logic of the system?
I guess I should also ask: How hard should the b-pillar and rear console vents blow with fan set to highest setting?
Last edited by Benz-O-Rama; Jan 12, 2010 at 09:40 PM.
Does a document exist that can educate me on the logic of the system?
I believe SDmedia has better data on this than WIS.
Considering automatic air flow control, isn't this always the case unless you manually select certain air flow setting. Like if the fan speed is set manually, the system does not indicate it is on automatic mode any more but it still controls the rest automatically except the fan speed. It should be the same if fan speed was set to automatic but the air flow was controlled manually (I guess even possible for one side only, I'm not sure).
Maybe your car has jealosy issues of the new R230?
Funny you should say that. I'm not lying when I say 2 days after I brought the SL600 home, portions of the keyless-go system stopped working on the E500. Now this...
She's very angry with me.
Not to mention, I think she went online and saw this....
Did you ever figure this out? I have a 2003 E500 with the same issue. The codes I'm getting are 93F8 Communication error of AC bus with component M16/30(Left rear blending air flap actuator motor) and 9380 Communication error of AC bus with component M16/31(Right rear blending air flap actuator motor). Would both motors go bad at the same time or do I have another issue?
Could be your operating unit (n22/7), see attached block diagram. Not sure if this will reveal anything in your case but in case you do not already know unit should have diagnostic mode: https://mbworld.org/forums/mercedes-...tml#post267715
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