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1999 ML430
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15 Posts
Discussion Starter #21
Maybe it is time you considered replacing the Blend Door Motor. Look at the repair instructions in the below link.

It might look like a headache to do but it really isn't. Just 15 or so screws hold the top skin (very light) on and everything is exposed.

Also, if you intend on doing it, I would suggest buy the OE motor as you do not want to do this again in 6 mos.

http://www.benzworld.org/forums/w163-m-class/1417771-diy-thread-collection-5.html#post4763314
Mission accomplished! Took me a long time over the weekend, I went very slowly and methodically to make sure I didn't damage anything. Only minor thing was one of the clips for the A pillar trim panel fell inside the frame while I was re-installing, not a big deal.

The new OE motor (from parts.com) works fine. I did have a bit of a scare when I first installed it and tested the AC with everything still disassembled, and it moved to the hot position and stayed there. Then I realized the temperature sensor (on the Low Range switch panel) was disconnected, re-connected it and hey presto the blend control started working. Not sure what was up with the old motor. Disassembled it and no broken cogs, so I guess the motor must have burnt out.

I'll post some additional tips with pics later that might be useful to others attempting this.

On to my next project, a faulty switch in the interior dome light, and bulb replacement in the trip computer. Already see some threads on those...

43sqd, thanks for your help!
 

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'07 ML350, '05 ML350SE, '04 ML350, '01 ML55, '05 SLK350, '04 SLK200, '76 280SL
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1999 ml320,05 cls 55 amg
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162 Posts
Thank you 43sqd finally found the post about removing dash. I could here the click of the blend door motor at the middle position between hot and cold. what a pain in the ... to get the glove box off, thought something plastic was going to break but nothing did. I fixed mine for now by tapping the plastic arm with long screw driver and now its moving fine. going to put some more grease on it and hope it works through the 3 winter months we have down here in texas. I am leaving the glove box out for now
 

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1999 ml320
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64 Posts
The easiest and cheapest way to this problem is to replace the N19 module with a used one. If after replacement, the exact same problem exists, then we will have to do extensive tests or go a different route.

Below is a list of N19's for sale on ebay. I would choose the $30 one (second link below).

Post back with results.


denso tn277300-0471 in eBay Motors | eBay

98 99 00 01 02 03 04 05 Mercedes W163 ML320 ML430 ML55 Air Control ECU Module | eBay
hey 43sqd, im lost which by the way isnt hard :)
my a/c is blowing hot and the line is cold under the hood so i decided to try the n19 relay to see if it would fix,went to look at the linx u showed like this one https://www.ebay.com/itm/1999-Mercedes-Benz-ML320-W163-CLIMATE-CONTROL-SWITCH-MODULE-TN277300-0471/273570928385?epid=1337394946&hash=item3fb2191701:g:yGMAAOSwysFb9GIX and it is in no way shape or form like the n19`s ive found here? https://www.ebay.com/itm/NEW-ALLEN-BRADLEY-AB-HEATER-COIL-ELEMENT-N19-THERMAL/290028629129?hash=item43870dac89:g:GmwAAOxyQqBRHSMw can u tell me which one is right and what mine is vs. yours? thnx bb
 

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1999 ml320
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64 Posts
Sorry the N19 did not work out but it was the easiest way out.

I probably should have made you do this test before telling you to order N19, but put the center section back in place with the white tube connected. Turn the key to pos. #2 and hold a small piece of paper at the grille and see if it stays in place.
hey i kno this is old but 43sqd, im going to buy n19 from ebay but i noticed u said it was a 12-pin connector, the ones on ebay (same [email protected]) are 14-pin any ideas?
 

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1999 ml320
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64 Posts
Here is a boat load of them on ebay.

Search for MB part 2773000471.
well i got my n19 today and i pulled the radio out with 2 of my wifes nail files by the way:) worked great, was able to have her undo screw thru radio hole with a phillips bit and 1/4 inch ratchet, with out pulling temp knobs off just using radio hole and swapped n19`s and slapped back together a/c worx great again thnx for all help and input once again:)
 
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