B Class W245 Air-Con on or off?

[Jason1145]

Shoot me down if this is a shootable question..... but my A/C button says "A/C Off"
So when I switch the fan speed from 0 to number 1 this "A/C off" button lights up..... so is the aircon on or off?????????
Only had the car a couple mnths with minimal driving so nt had enough time to sit n test it out and only occurs to me once I'm out the car .. groan!
Also want to make sure the A/C is working ready for summer when it finally arrives.

Normally I would expect the light to be on when the A/C is on.

Any help appreciated.

 

[kid-jensen]

The AC is going off when the lamp lights up.

I'd check why this is.. Might be deliberate behaviour, but it sounds like the controller has detected a fault ond disabled the AC, hence trhe light.

Info ion the operation of the "AC off" light sahould be in the Ownwer's manual.

If your outside temperature is anything like as cold as Crawley High Street this lunchtime, now would be a good tome to get the AC fixed before the warm weather arrives and everyone discovers thery need AC repairs at the same time...

 

[Jason1145]

Hi Paul

Just to double check....... the button for my a/c control has the printed words "A/C Off" on it with a led on the same button.

Just in case you might have thought I meant I was seeing "A/C off" as a warning message somewhere on the dash or something?

So... this button lights up when I put any blower speed on.... does this led lighting up mean that the AC is off (as the button says "A/C off") or it's on lol?

I should read the manual tonight if I remember... and yes London has a chill wind today too which I love!

 

[Deleted member 113659]

If the light is on the AC is on. The reason the light goes out when the blower turned to 0 is the whole system shuts down.

Press the button when the blower is on and you can use the whole system without AC on.

Hope my ramble made sense mate.

Ant.

 

[Codger49]

I think there is some confusion here.

As I understand it Mercedes traditionally had a button labelled 'A/C Off', when this is illuminated the AC is off. Sometime in the 2000s, Mercedes changed the button to light up red when the AC is on and removed the 'Off' text, as was normal with other manufacturers.

My 2006 CLK with automatic AC has its AC button labelled 'A/C Rest' and I understand illuminates red when the AC is on. Our 2002 A190 has the A/C Off button and illuminates when the AC is off.

Hopefully, an expert may come along and tell us when the change was made for particular models.

 

[BTB 500]

Yes, the M-B 'rule' is that the LED shows the function written on the switch is on/active. So if the button says "A/C Off" the light means it's off ... and if it says "A/C" the light means it's on.

My SL has an A/C Off switch, whereas the Vito and C Class have AC switches!

The "Rest" function is something else BTW. That only works with the engine off, running the fan at low speed to use residual heat in the engine to keep the car warm for a limited time (after which it turns off).

 

[Deleted member 113659]

Sorry for my post guys. I think I've got it now. Light on our car is just A/C. (Not A/C off) Just looked.

Ant.

 

[BTB 500]

The Vito has a whole row of double-sided rocker switches controlling things like the various interior lights, and it took me about a year to crack how they actually worked

 

[whitenemesis]

From the WIS doc for the 203, 219 & 211

"Display logic of function LED in the AC button (7)
For vehicles up to 31.5.05, the function LED is off when the refrigerant compressor is on.
For vehicles as of 1.6.05, the function LED is on when the refrigerant compressor is on."

Just to be aware the display logic has changed over time. Your owners handbook will explain

 

[GLK]

There are two types of control panel for a/c system on W169 and W245 - pre-facelift has AC off button and facelift - AC button.

The button activates / deactivates cooling with dehumidification.

For the former, when the red light is on, the function is deactivated; for the latter - activated.

This was changed without too much fanfare, some of the new units came even before the facelift, even some manuals are mismatched. Certainly the online interactive manual only refers to AC button, i.e. the new type unit.

I have the old type controller and my AC off button is never lit. A/C works perfectly.

To answer the OP question - there's something wrong with your a/c system:

A/C should be on by default, when you start the car, and if it is switching itself off, well ... as above.

One other button that changed is the rear windscreen heater - old version only has an icon, the new one also says REAR.

New unit:

Old unit:

 

[GLK]

I see that, during the time it took me to get the screen grabs and find and edit an old pic of my climate control unit, etc, etc, the question has been answered a few times

 

[Jason1145]

Thanks a bunch guys some interesting info there.
So GLK, you think my AC has a fault because when I switch the blower on from zero to any number my "A/C Off" button light comes on which indicates the AC is off?
You mean the AC should automatically come on and mine doesn't so its faulty?
Is this how other W245's work?
I couldn't see this explained in the user manual last night, tbf though there is over 20 pages explaining the whole system.... All I want to know is when I feel hot hot how to make it cold and vice versa lol.

If it wasn't so damn cold right now ( -1 in London) I'd be able to tell what is AC cold but everything is cold brrrrr!

 

[GLK]

What happens when you press the [lit] AC off button?

If the light goes off, then everything is fine, if not, or if it behaves like described in the second paragraph of the screenshot above, i.e. light flashes three times and remains on, then, yes it is faulty and needs to be checked on STAR, etc.

It might be something as simple as blocked dust filter, or [worse] damaged condenser, etc.

Also, don't keep the airflow switch on 0 - it's not good for the A/C system.

Once you get it checked, I'd do a good disinfection treatment (aka AC bomb) and replace the dust/combination/pollen filter.

 

[Jason1145]

I have the old type controller and my AC off button is never lit. A/C works perfectly.

To answer the OP question - there's something wrong with your a/c system:

A/C should be on by default, when you start the car, and if it is switching itself off, well ... as above.




Old unit:

This above section of instructions is not in my Manual, this is for the "new" unit with just the "A/C" button, so the guidelines are for the other unit, not mine.

Mine is below... the "old" unit

This is from my manual....

MB like to make things complicated I see.

In answer to the question... when I press my "A/C off" button I can make the light either stay on, or go off so I guess it has no error... wish it was hot so I could properly test it now.

 

[GLK]

Yes, that's what I was trying to explain - same function, but different logic for old and new units (also see post #9).

As long as you can turn the light off, and it stays off, your a/c is okay.

Keep the airflow on 1 and AC off button not illuminated.

Disinfecting the system and replacing your cabin filter is still a good idea for newly acquired car. If you want to combine disinfecting with re-gas, Mercedes Sytner got a £49 offer going at the moment.

 

[Jason1145]

Cool got it thanks, airfow 1 with button light out.... I tried one of those spray cans you set off in the cabin then close all doors with a/c on full for 20 mins while you stand outside it like a lemon.... didn't fix that bad odour the a/c was suffering from but that was a works van which had stagnant water sitting in the system and that wouldn't have fixed it ;p

 

[GLK]

When I bought this A200 last year, I did sort of multi-phase treatment - foam into vents, then all front vents out and clean, then the spray can, and then thorough cleanup of the filter housing, including checking water drains, and a new OE cabin filter. Not a whiff since, and I am very picky ...

If your a/c needs re-gas, that Sytner MB offer is not a bad value for money.