GuruGuy

2004 C230K. Question about the climate control - defroster. When selecting the defroster "button" and it disables the auto function, is it also necessary to select the defroster setting with the knob that points up only? I'm confused as to why there would need to be two adjustments??? Of if simply pressing the defroster button activates the defroster, then why is there also a setting for it on the knob?

Lynn

For maximun defrosting, just hit the defrost button. Nothing else needs to be done. As you know, that will override the automatic function. You can turn off the automatic function and use the fan speed knob and the air flow direction knob to set the heater to send the amount of air you desire to the vents you desire.

GuruGuy

I guess I don't understand why there are two "manual" ways of turning on the defroster.

#1 Hit the defroster button, it disables auto mode and directs air to windshield??? Does this only run at high fan speed???

#2 Disable auto mode, adjust fan speed, and direct air to windshield with airflow direction knob.


If using #1 above, is it necessary to set the airflow direction to the windshield?

Lynn

#1 Hit the defroster button, it disables auto mode and directs air to windshield??? Does this only run at high fan speed???

Yes and Yes.

#2 Disable auto mode, adjust fan speed, and direct air to windshield with airflow direction knob.

Yes, and you can also use the the air direction knob to split the air flow to a selected combination of vents.

If using #1 above, is it necessary to set the airflow direction to the windshield?

No.

mctwin2kman

Actually my fan slows eventually from high speed to lower speed. And the up arrow on the vent selection does not do as much as the defrost button does. Defrost activates the AC compressor to get the moisture out of the air and remove the fog from the windshield. Where the selection knob stays on auto and depending on weather conditions will not cycle the AC compressor. My old 190E does this as well. Hence why the windows fog while on auto even though the interior is warm, especially if you hit the AC off button during winter months.

GuruGuy

It's my understanding that the a/c will be on in ALL modes unless it is manually turned off with the A/C off button. I don't understand why there are three ways to use the defroster in this car.

Auto

Defroster button (disables Auto)

Auto off, Defroster button off, and Airflow direction set to UP (windshield) with fan speed and temp controlled manually also.

mctwin2kman

Just because the button is not off does not mean the AC is not off. That just disables the AC compressor all together. There are many other sensors that control the AC compressor, the only way to force it to come on is with the defrost setting for the front windshield. This is the same on all cars built in the last 20 years or more. Even my wifes Saturn does this. As for multiple ways to defrost, also only one true way and that is the defrost button. If set to auto it will auto shift the vents around to its liking to obtain the desired temp. The upper arrow does not lock on the AC compressor, nor does it defrost the windshield anywhere near as good as the Defrost Button. There is a reason that the defrost button is there and has been on MB's for some time. And it is not just to add another button, it serves a very specific purpose and does it very well in my opinion. My only dislike is not being able to slow the fan down, but I guess the Germans want it done as quick as possible without the driver needing to touch anything but one button. This could be very helpfull at 100 plus miles per hour.

GuruGuy

I've noticed that I can adjust the fan speed on my 2004 with the defrost button on....if I just turn the fan speed up a notch and then back down, it goes to where I have set it at.