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Discussion Starter #1
Hi to you all out there.

What is the difference between the two and does one rather than the other have a detrimental effect on the demist function when following the owner manual advice ?
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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AC should be on (with air being directly to glass) to dehumidify the air otherwise won't it freeze up on the inside of the windshield?
 

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Discussion Starter #3
Hi LdB. I have carried out the procedure as described but the unit in my car has recently been changed for a Pre
Owned unit after the original one failed on the fan speeds.
I am aware that the AC will dry any incoming air so as to demist properly in the fastest time.
The unit is marked EC not AC as was on the original one that failed on the fan speeds;my question was is there a difference between EC & AC.
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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Assuming EC is "evaporator coil" and ac is air condition(er), this link relates to home hvac systems but maybe your unit was incorrectly replaced with the wrong unit ??

It explains the role of both items:

This maybe totally out in left field (in the parking lot even) but as no one else has jumped in......
 

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Discussion Starter #5
Hi again LdB. I have just checked in my owner manual and the image is of the hvac unit with an AC button not an EC button.
I had this seemingly incorrect unit/panel fitted a few months ago after the original panel with an AC button failed on the fan speeds.

I will contact my local'ish MB Dealer and probably will get a fright when I ask about an OEM replacement unit.
I will also do some searching for one the same as that which came out.
 

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Registered 1996 SLK230K
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In my '96 230K I have the EC button. The way mine works is that the AC is always on, unless the EC button is pressed and the buttons light is turned on.
This led me to believe that EC stood for "Economy", as you aren't using the AC compressor thus reducing parasitic losses.

Cheers
Jay

EDIT: The status of the EC button (on/off) is maintained when the vehicle is switched off and restarted.
 

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Discussion Starter #8
Hi Jay. Thank you for your well explained input but what I am not sure of is whether the electrical connections at the back of the switch are interchangeable/compatible and actually perform the very same functions but in a different way.

There are some very early panels out there that only have two switches that appear to be a heated rear screen switch and an air re-circulation switch and no AC or EC switch.
 

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Premium Member 2001 SLK200K, 2001 SLK320
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There are some very early panels out there that only have two switches that appear to be a heated rear screen switch and an air re-circulation switch and no AC or EC switch.
The "very early panels" as you put it, are not early panels at all. They are the Controllers for non-AC equipped cars, commonly the 200 and 200k.
 

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Discussion Starter #10
Hi Marcus. Thank you,I was not aware that the early cars and especially the 200 & 200 compressor were so basic especially when considering what other premium car manufactures were offering as 'goodies/toys' even in the entry level models.
 

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Premium Member 2001 SLK200K, 2001 SLK320
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Not necessarily early, air con was an optional extra on the 200 and 200k's at least. My 2001 200k does not have AC. .. whilst the 320 which is 9 days newer does.

HTH
 

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Discussion Starter #12
Hi again to you all out there. I have arrived at a provisional conclusion regarding the title of my post !!

I only changed the panel because of a failure with the fan switch that was diagnose as not fully functioning on the mid-range speeds albeit at that point I had not had a need for checking out the demist setting and whether it was fully functioning (the flaps were being opened and directing air up-to the screen.

The replacement switch (EC button) works otherwise OK except for the demist function which does not produce a flow of air even though the setting according to the user manual are being used.

This leads me to thinking that; 1) there is an electrical fault on the appropriate pin and or the signal is not being transmitted to the flaps control.

2) there is a linkage issue behind the dash with the rods that control the flaps.

The second scenario is apparently an expensive fix and and seemingly needs the dash area taking down for examination/fixing. This is not one for me and as I do not have anywhere for working that is under cover.

Is it a wise move spending/investing in an otherwise very tidy SLK 230 Auto in Cubanite Silver Metallic or is a now time for calling it a day and living with this issue and manually demist when required.
571862
HTC One M8 17-01-20 SLK 230 on R171's 001.jpg
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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You say you had it changed a few months ago. By you or a shop? If by a shop, what do they say? Still under some sort of warranty?

Depending on your situation, if you're planning on keeping it for a while, I personally would get it done. If you keep it and decide not to get it repaired AND if it really starts to be a downer 3-4-5 months down the road, you'll wish you had it done "months ago".

Your ride is 16 years old. You are ALWAYS going to have one thing or another go wrong at times. This is one of those times.

I read a few of your prior posts (after you bought this car). Had a few niggling issues (paint, key, etc) which you IIRC resolved. Nothing major. BUT you resolved them. This is another niggling issue as I said.

You do like/love your car right? SO, stop waffling about it, get it done and get on with happy motoring.
 

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Discussion Starter #14
Hi Len. The unit was bought off of E'bay and fitted for me by my MB Independent.

The fan then worked in all positions but I can not vouch for in the air coming through the vents and onto the windscreen,at that point it was Spring and demist was not needed so not tested for either.

It was him that told me that getting at the directional flaps for the windscreen demist was a major job and entailed stripping out the dash board and other areas so as to gain access.

The niggling things that you refer to totalled some £1200.00 within the first 6 months/3,000 miles of buying the car.

I was in an earlier SLK 230 Auto yesterday that was fitted with the unit/panel that had the EC button and the flow of air to the screen was powerful;surely that would indicate that despite the notes in the Lennox link that you provided me with 5 days ago that the 'behind the dash' parts do one in the same job !!

https://www.lennox.com/buyers-guide/guide-to-hvac/glossary/evaporator-coil

A brand new panel with all switches is some £400.00 pounds and then needs fitting with no guarantee that flaps are functioning correctly when the electrical signal at the switch is activated.

There is also some doubt that the exact same one that was fitted (OEM) is available anyway !!






that you provided
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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Super Moderator UK 2002 SLK320 Blue
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I'm a bit late to the party (power issues here due to the storm) but @Andjeti is spot on with his description of the 'EC' button.

I'd be inclined to check how the plastic spigots on the control knobs 'connect' with the heating controls in the dash as these may not be lined up to work as dialed. It does mean taking the centre dash off again, but you'd need to do that to address the problem anyway. This may help you find the right screw locations (although I expect you may know this):
 

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Discussion Starter #18
I'm a bit late to the party (power issues here due to the storm) but @Andjeti is spot on with his description of the 'EC' button.

I'd be inclined to check how the plastic spigots on the control knobs 'connect' with the heating controls in the dash as these may not be lined up to work as dialed. It does mean taking the centre dash off again, but you'd need to do that to address the problem anyway. This may help you find the right screw locations (although I expect you may know this):
Hi savcom. Thank you I found the YouTube video was OK but I do not speak German and some of the shots were slightly obscured,that said the alternative video that actually showed the two white plastic spigots being inserted into their housings was helpful.
Having watch the various videos the only thing that I am a bit uncertain about is pulling the auto shift stick up and away.
 

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Discussion Starter #19
After studying the backs of both dials on then I have come to the conclusion that the demist 'flaps' that operate by an electrical signal that allegedly operates rods or a single rod must be where to lack of airflow lies !!
What then do the two white spigots do other than direct vents/flaps for the other functions of directing the air flow that the fan speed creates onto the parts of the body/interior as directed on the dial.
 

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Super Moderator UK 2002 SLK320 Blue
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I think that was a manual stick he was playing with in that car - my Auto stick does go back with enough clearance - and one fiurther tip is to pop the drinks holder out and put it somewhere safe. Eject the holder and you can insert a long thin screwdriver into a small slot in the centre underneath the tray to release a catch and the tray slides forward and away. Then you've more room to play.
 
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