Can't turn off air con

[Dizz]

I have just bought a 2004 CLK320 w209 and what ever I do the air-con seems to be on.
What am I doing/not doing?

This is off?

This is on?

 

[bob6600]

First is on, second is off

 

[markmifsud]

would also help if you didnt have your temperature controls set to minimum

 

[clk320x]

I don't get why they have it so LED on is OFF... lol

 

[John]

You should run air con all the time to stop the seals drying out allowing the gas to escape.

So the default should be on and you wouldn't want one of the lights on indicating the air con was on all the time as the rest are set to be off all the time they are not used...

 

[Dizz]

I don't get why they have it so LED on is OFF... lol

Hi Abs, i hoped you would see this post as I think you have the same AC controls.
Does the aircon kick in regardless of the switches positions (pic 1&2) if the temp dials are set to low temp?

 

[markjay]

I don't get why they have it so LED on is OFF... lol

When the red LED is on, the function is activated (AC, Auto, etc).

When the red LED is off, the function is not activated.

EDIT: only after 01/06/2005.... see WN's post below.

 

[markjay]

Hi Abs, i hoped you would see this post as I think you have the same AC controls.
Does the aircon kick in regardless of the switches positions (pic 1&2) if the temp dials are set to low temp?

No.

If the temp dial is set to 'low' an the aircon is set to 'off', you will simply get unheated air i.e. that did not pass through the heating matrix, meaning the air will be at the ambient external temperature (more or less).

The AC can only be turned on from the AC button.

 

[whitenemesis]

I don't get why they have it so LED on is OFF... lol

From the WIS doc.

Display logic of function LED in AC button/REST button (8)
On vehicles up to 31.5.05, the function LED is off when the refrigerant compressor is switched on.
On vehicles as from 1.6.05, the function LED is on when the refrigerant compressor is switched on

 

[markjay]

From the WIS doc.

Display logic of function LED in AC button/REST button (8)
On vehicles up to 31.5.05, the function LED is off when the refrigerant compressor is switched on.
On vehicles as from 1.6.05, the function LED is on when the refrigerant compressor is switched on

That explains it... my W203 was 2006.

 

[cheddar]

I've also noticed over the years working on these cars, when checking the AC, even after it is turned off (ie. AC off/ECON on etc), the AC compressor continues to operate for a good few minutes. I suspect this is something in the software to give it a minimum operating time.
It does make testing the system confusing so I know exactly what you mean when you say it's hard to tell when it's on or off

 

[Dizz]

I've also noticed over the years working on these cars, when checking the AC, even after it is turned off (ie. AC off/ECON on etc), the AC compressor continues to operate for a good few minutes. I suspect this is something in the software to give it a minimum operating time.
It does make testing the system confusing so I know exactly what you mean when you say it's hard to tell when it's on or off

There is a noticeable reduction of forced air (fan speed) when switching on/off but it stays cold no matter what I do, probably because as you say.


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[Dizz]

From the WIS doc.



Display logic of function LED in AC button/REST button (8)

On vehicles up to 31.5.05, the function LED is off when the refrigerant compressor is switched on.

On vehicles as from 1.6.05, the function LED is on when the refrigerant compressor is switched on

So in this pic the auto circulation is on and the air con is off?

 

[Codger49]

Yup.

 

[whitenemesis]

Yes, air volume, distribution and temperature is automatically controlled and the a/c compressor is off, incoming air will not be cooled.

 

[Dizz]

Ok so it seems I have had the AC on and when switching it off no temp change was happening as it takes a while for it to take effect thus causing me to question what was happening.

Next question is...does the AC have a big/small effect on MPG?


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[whitenemesis]

In my experience in both the S203 (270cdi) and W209 (55AMG) no effect on mpg whatsoever.

Best advice is to leave the a/c switched on at all times. It helps keep the system seals lubricated and your windows mist free