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  #1  
Old 08-03-2006, 04:30 AM
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Unhappy No Air from the Center

Can anyone suggest to me what could be wrong with my car..it is a 86 300E ..I have air coming from every vent except the center one..u can hear the blower motor working but some how no Air comes out from Center vent. Driver side vent has good flow of Air and I get air blow from the bottom vents but nothing from the center vent...pl HeLP

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  #2  
Old 08-03-2006, 06:42 AM
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The vacuum element that controls that door probably has a leak and it need to be replaced. The dash needs to be removed to replace it.
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  #3  
Old 08-03-2006, 09:25 AM
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You should also check the solenoids located in the right side of the center console. I think they are called change-over valves. They apply the vacuum going to the elements and eventually burn out. I tested all mine and replaced 3 bad ones.
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Old 08-04-2006, 05:22 AM
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thanks for the reply

thank you all for the advice..I had to take the glove box out and had to tie down the vaccum unit so no air went to the vents near the windshield and kind of opened up the center vents..now I am getting some air from the center vent..but it is just a quick (temp) fix..do I need to replace all the parts controlling the vents..for it work..or could it be some thing else or if some one can suggest what I should do and parts should I order..thanks guys
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Old 08-04-2006, 05:31 AM
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Go look over in the diesel section for fixes.
Diesel member's fixes range from replacement to coat hangers and they all direct flow to the center vents.
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  #6  
Old 08-09-2006, 06:09 PM
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JP. Am having similar problem with my '90 300E. Seems to be vacuum related. Have been told by mechanic that the flap-actuating vac solenoids in the dash are difficult to access. He is an independent M-B tech with lots of experience. He has a "vacuum system analysis" that he claims will pinpoint vac element problems and costs about $79. This, of course, is not including any repairs or parts. Anyone heard of this procedure? Am considering it, in the meantime will watch this for additional posts and add any info I can.
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Old 08-09-2006, 07:20 PM
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The vacuum element circled in red is the one that controls the center vent. This is photo of one from a 1992 300 TE.
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No Air from the Center-evapdone-003.jpg  
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  #8  
Old 08-10-2006, 11:55 AM
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Crikey! Dealing with that convoluted mess looks like more than my limited budget and/or wrenching skills can manage. Can the center vents be blocked open mechanically and then restored to "normal" when the weather turns cold? Or is there a chance the problem is in one of the switching vac-solenoids that are easier to access?
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  #9  
Old 08-11-2006, 02:13 PM
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Check the vac solenoids first. Unplug and check each one with an ohmmeter. Replace the ones that are open. You can also apply 12V and listen for a click. The one for defrost is powered all the time so it is the most likely to burn out. My car has individual solenoids which are interchangable with each other, so you can "borrow" a known good one to make the defroster close.
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  #10  
Old 08-12-2006, 03:26 AM
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cdplayer

I have a 1984 500 SEC. I too could not get air from the center vents. Found info on another topic within the 126 forum where guys used a long screw driver through the vent with a flash light to push the flap open. Of course this is a temporary fix but the flap stays open all the time and air flows freely. As for my car, there are sliders on the dash to open or close the vents. My center vent slider moves but is not attached to the flap.
I can live with that for now. Makes dealing with the 100+ degree weather out here in Cali.
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  #11  
Old 08-15-2006, 03:47 AM
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u r lucky

Quote:
Originally Posted by cjlipps View Post
JP. Am having similar problem with my '90 300E. Seems to be vacuum related. Have been told by mechanic that the flap-actuating vac solenoids in the dash are difficult to access. He is an independent M-B tech with lots of experience. He has a "vacuum system analysis" that he claims will pinpoint vac element problems and costs about $79. This, of course, is not including any repairs or parts. Anyone heard of this procedure? Am considering it, in the meantime will watch this for additional posts and add any info I can.
cjlipps u r very lucky that you have such a mechanic..my mechanic has told me that it is going to cost $700+ to fix the problem as he is going to replace all the solenoids (he said there are 7 Solenoids which r involved) so he wants to replace all of them..it does not matter if they are good or bad. I don't know if he is on the right track or is he BS*ing me.
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  #12  
Old 08-15-2006, 07:01 AM
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Quote:
my mechanic has told me that it is going to cost $700+ to fix the problem as he is going to replace all the solenoids (he said there are 7 Solenoids which r involved) so he wants to replace all of them..it does not matter if they are good or bad
I've done this job on three 124's and they only had 6 vaccum elements. I do agree that if you are going to remove the dash to go ahead and replace them all. Of course I'd replace the evaporator too if you have the dash off and since you have to take the evap case apart to replace one of the elements which is inside the case.

Finally, your mechcanics price seems low to me especially if it includes parts too. I'd ask him how many times he has done this job.
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  #13  
Old 08-15-2006, 03:22 PM
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Thanks Ron

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Originally Posted by Ron in SC View Post
I've done this job on three 124's and they only had 6 vaccum elements. I do agree that if you are going to remove the dash to go ahead and replace them all. Of course I'd replace the evaporator too if you have the dash off and since you have to take the evap case apart to replace one of the elements which is inside the case.

Finally, your mechcanics price seems low to me especially if it includes parts too. I'd ask him how many times he has done this job.
Thanks Ron..thanks for telling me this..now I feel much better, he told me he has done a few times, and infact his wife's car has the same problem and he has told her to live with it ( I am still thinking whether to get it done or not..may be I can save some money if I bought the Vaccum elements online and paid him for the labor only. I don't know where to find the elements..if anyone has any suggestions pl let me know..I am so glad that I joined this forum..learning a lot. By the way got my A/C fixeed today..got the compressor replaced but still it was not working good enough so he suggested me to change the Fan Clutch and that took care of the problem plus the car does not get hot in traffic (California heat).

Now I have two problems left to get fixed..one is that my mileage has dropped a lot (it is less by nearly 100 miles on a tank) and the second problem is kind of minor but irritating..when I open the driver side door the buzzer does not work (when the key is in the ignition or if the lights are left on) and the dome light does not come on..but if I open the passenger side door it works fine. It is not the switch on the door we checked that..seems to be some other problem..any suggestions..any body (especially Ron)..thanks
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  #14  
Old 08-15-2006, 04:03 PM
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With that bad a mileage I’d think I had a fuel leak, like the hose back by the fuel tank that goes to the fuel pump.

As to the door switch, I know you checked it. I’d probably remove the door switch from the passenger side that you know works and try it in the drivers side door. Unless that's how you determined it was not the switch.

If you have all the vacuum elements replaced the evap box has to come out and be taken apart. If you do that I can not imagine not putting in a new evaporator, the cost of the parts is very small and there is really not much more labor to put in a new evaporator once everything is apart.
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  #15  
Old 08-18-2006, 06:11 PM
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Well, I delved into the dash this afternoon and found the vacuum block mounted vertically just to the left of the glove compartment. It has a vacuum source on the top and 7 vac lines attached along one side with an electrical plug near the bottom. Probably 1"X1"X6". I removed each line individually and when I applied source vacuum to them directly the respective actuators seemed to work fine. I checked the records on the car and this part (vac block) was replaced about 9 months ago. My original complaint was the air from the center vents seemed dependent on total vacuum. In other words, it would cease under acceleration and return as I leveled out at speed. As time has gone on, there is no air at the center and the defrost vents are blowing like crazy. This has gotten worse gradually and the overall impression is that the flappers are doing as they darn well please. The question I'm getting to is: Can the failure of the vacuum block cause all this and what are the odds of it failing again so soon? (The original failure was marked by no air coming out of the footwell vents while in heat mode during the winter.) Also, the vacuum block was quite warm to the touch during operation. Thanks to all for a great site. I've learned more in the few days since I discovered this forum than in my many prior years of Benz ownership.

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