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Hi all. I tried doing a search but was not successful. Probably my fault. Anyway, I discovered today that when I change the position of the vent control dial, (it's a 2004 230 kompressor) the air flow never changes, it only comes out of the dash vents. Not the defrost vents or the floor vents, only the dash vents. Anyone have this problem before or know of a way to check/fix this? I have had the control module out of the dash to investigate a problem with the lights behind the dials. Could I have put something back wrong? I've only had the car a couple of months and its been hot as you know what here in NC, so I have only been running the AC. Was just messing around today when I discovered this problem. Won't need heat or defrost for quite some time, but I would like to get it fixed before I do. Thanks!
 

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Hi there,

The vents on the R170 are controlled mechanically.

I am more than sure than when you put it back, you did not put it correctly, as it happened to me as well, before.

I would recommend taking it out, along with your radio system, to allow more space.
Then, when you put it back, you should feel with your fingers, that the male connectors fit into the female ones on the wall.

You will have two male connectors, and one is shorter than the other, so make sure you fit the longer one first.

You should also take notice that the valves are correctly calibrated, to be in the position that is shown on the climate control module.

The female connectors have square entrances, with a little dent on one side.

If I remember correctly (I may be wrong), the dents should be on top for both connectors, when the rotating thing that control the position, on your climate control module is at 12 o'clock.

Let us know if you sorted out your issue :)
 

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Wilhelm, you are 100% correct! I went out this morning while it was cool and took the console apart. I felt up through the radio opening and lo and behold, the shafts were not in the couplings! Ha! I put it back together wrong from the last time. I didn't realize that those shafts and couplings were that flexible. I reconnected them and checked the operation before I put everything back together. Then I also got out the owners manual (DUH!!) and read the controls section THOROUGHLY and saw that you have to MANUALLY close the dash vents to direct the full airflow to the floor or defrost vents. I've never seen a system like that before. All other cars I have had directed the air where the dial said it was going without doing anything else. Anyway, thanks for the reply and I'm still learning the little quirks auf meine kleine deutsche auto!
 

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Wilhelm, you are 100% correct! I went out this morning while it was cool and took the console apart. I felt up through the radio opening and lo and behold, the shafts were not in the couplings! Ha! I put it back together wrong from the last time. I didn't realize that those shafts and couplings were that flexible. I reconnected them and checked the operation before I put everything back together. Then I also got out the owners manual (DUH!!) and read the controls section THOROUGHLY and saw that you have to MANUALLY close the dash vents to direct the full airflow to the floor or defrost vents. I've never seen a system like that before. All other cars I have had directed the air where the dial said it was going without doing anything else. Anyway, thanks for the reply and I'm still learning the little quirks auf meine kleine deutsche auto!



I was searching for something else related and came across this older post. I was confused and got my manual out (2001 SLK320 NA) and the need to close up the dash centre vents and outside vents is described as a short term need which I take to mean to scavenge as much heated air to windshield while the car comes to operating temperature. My manual does not describe a need to do this when the car is up to heat as you use these vents to warm the cabin as well as defrost the windshield.
 

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If I may borrow this topic,
I have a somewhat similar issue. For the first 10-20 km the air from vents is not blowing consistently. It will blow, stop (for 2-60 seconds), blow again, stop, ... After some time (never tried while standing, but after about 15 minutes of driving) it works as it should. This is regardless of AC, heating or "cooling" with AC off (having EC pressed).


Fuses all look good, I don't know if I should check any relays/sensors?
 

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If I may borrow this topic,
I have a somewhat similar issue. For the first 10-20 km the air from vents is not blowing consistently. It will blow, stop (for 2-60 seconds), blow again, stop, ... After some time (never tried while standing, but after about 15 minutes of driving) it works as it should. This is regardless of AC, heating or "cooling" with AC off (having EC pressed).


Fuses all look good, I don't know if I should check any relays/sensors?

I suspect you may either have a loose connection at the resistor that controls the fan or it is telling you the resistor is on its way out. One of these days the fan will not come on at all is what I am betting, It almost sounds like one the heat builds up the fan circuit becomes stable.



This is a test that will perhaps shed some light on it.


The three prong connection that attaches to the regulator(resistor) should always have power from the red lead, the brown lead is ground, and the white/pink strip lead is controlled by the fan switch. With the car off, and the fan switch in the "off" position, there should be no power to the white/pink lead. With the car on, the voltage to the white/pink lead should increase as the fan switch is rotated from "off" to "high".

If there is constant power to the white/pink lead, the control panel is defective. If there is no power to the white/red lead, but the fan still runs, the regulator(resistor) is defective. That's my issue - no power from the white/red lead, but the blower motor still runs. This is a common problem - the regulator(resistor) fails "closed" and provides power to the fan without power from the controller (fan switch).

Resistor PN A 202 820 73 10
 

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Thanks! I googled that this regulator should be under the glove compartment, somewhere next to the cabin filter. I will check that and hopefully fix the issue :)
 

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Thanks! I googled that this regulator should be under the glove compartment, somewhere next to the cabin filter. I will check that and hopefully fix the issue :)
Sorry about opening an old topic, I am very curious of the regulator was bad for you and it fixe the issue? I can control the speed, but I have the same issue with no ability to direct air to the front window, or floor.
 

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Sorry about opening an old topic, I am very curious of the regulator was bad for you and it fixe the issue? I can control the speed, but I have the same issue with no ability to direct air to the front window, or floor.
As Alex says, if you have fan speed control, it's not a regulator/fan issue
 

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Hi,

It is mechanically actuated, you just got to remove the HVAC Panel, and hope it is obvious from there, i.e. one of the 2 link rods is not turning ............ = replace HVAC Controller ..............

If it is something in the Heater Box it is likely a take half the Car apart to get it out jobbie :surprise:

HTH, Cheers Dave
 

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Hi,

It is mechanically actuated, you just got to remove the HVAC Panel, and hope it is obvious from there, i.e. one of the 2 link rods is not turning ............ = replace HVAC Controller ..............

If it is something in the Heater Box it is likely a take half the Car apart to get it out jobbie <img src="https://www.slkworld.com/images/SLKWorld_2014/smilies/tango_face_surprise.png" border="0" alt="" title="EEK! Surprise!" class="inlineimg" />

HTH, Cheers Dave
Thanks, does this mean all the plastics have to come out again to get to the controller? Time to visit YouTube for a how to vid, thanks.

Here’s hoping it’s not the heater box you mention!

Update: Watched a video this morning and it seems fairly simple to gain access to the controllers.
 

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Hi @subwiz ,

Yes getting the Centre Trims etc out and then HVAC Panel is very easy :wink:

The HVAC Box however is a royal PITA, even the upper Dash Top panel has to come out, plus all the A/C and Heater Pipes off where they go through the Bulkhead, HVAC Boxes are usually a Bear, did one on a W221 S Class a while back, around 14 hours first time, could probably do the next one a little quicker :wink:

R170 is at least, not as complex as that one ;)

HTH, Cheers Dave
 

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14 hours!!!

I can only hope something has worked itself loose from the recent center console install, which I'll check soon enough, after that I'm going to hold off fixing for now. I've only had the car about 3 or 4 weeks, I feel it might be a good idea to make sure nothing 'dramatic' happens over the next few months.
 

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14 hours!!!

I can only hope something has worked itself loose from the recent center console install, which I'll check soon enough, after that I'm going to hold off fixing for now. I've only had the car about 3 or 4 weeks, I feel it might be a good idea to make sure nothing 'dramatic' happens over the next few months.

If you are in doubt used assemblies are about $125 and re-manufactured units for $175 plus shipping of course.
 

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14 hours!!!

I can only hope something has worked itself loose from the recent center console install, which I'll check soon enough, after that I'm going to hold off fixing for now.
What recent centre console install?

If you've been pulling the radio about or changing it for another head unit, there's a good chance that you've knocked one of the male finger thingummy's out of one of the female receptacle thingummy's - probably the shorter one of the two
 

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LOL @subwiz ,

14 hours was R&I Dash and HVAC from a 2008 W221 S Class, just for comparison purposes :wink:

I've never done full dash out on an R170, only all the panels below the Dash Top, HVAC box stayed in, I'd guess 6 hrs total on R170 when you've done it once before, and assuming some numpty hasn't been in there before and lost screws, spire nuts and busted trim and wiring clips, cos that all takes time to sort out properly !!

I agree with @M4rCu5 , you didn't mention the previous panels were removed, so yes, knowing that little nugget, I agree, it is likely a "dislocated finger" .............

Sounds painful :wink:

HTH, Cheers Dave
 

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What recent centre console install?

If you've been pulling the radio about or changing it for another head unit, there's a good chance that you've knocked one of the male finger thingummy's out of one of the female receptacle thingummy's - probably the shorter one of the two
I had a shop replace a lot of the interior plastics, so I'm going to hope that you are on to something! Will find out soon enough, need to order the tool to remove the audio.
 
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