Climate Control and Aircon

[television]

Also although it may be selected on the auto,, it is not running all the time,,only as needed

 

[rf065]

Tried just using the 'Auto' button yesterday WITHOUT the A/C light being on. I found that there WAS cooling. Thus the 'Auto' setting does switch the cooling compressor on. Is it just that without the A/C light on there is no dehumidification, although I would have thought with cooling comes the dehumidifying anyway??

I'd be very surprised if the air con is running in any way, shape or form when the A/C light is off, whether auto is selected or not.

(I know older MB's are different as when the light is off, air con is on)

Russ

 

[mikestrivens]

Is there a difference between air con, as fitted into most of the earlier models with three buttons between the rotary knobs, and climate control which has a completely different dash array ?

In my 1995 W124 price list option 580 air conditioning was £1947.50 and option 581 automatic climate control was £2562.50. So what is the difference? My guess is that air con is always working full blast whereas climate control is sensitive to the cabin temperature selector.

 

[survey]

I'd be very surprised if the air con is running in any way, shape or form when the A/C light is off, whether auto is selected or not.

(I know older MB's are different as when the light is off, air con is on)

Russ

I am sure when trying this on Auto only that it is not just ambient air being blown. I am struggling with the fact that it is difficult to get a definitive answer!

 

[Blobcat]

I think that "Auto" without the AC being on will keep the temperature of the cabin to what you set as long as it isn't below outside ambient temperature as the AC isn't running. It is an Economy mode.

 

[rf065]

I am sure when trying this on Auto only that it is not just ambient air being blown. I am struggling with the fact that it is difficult to get a definitive answer!

This is what Mercedes say about the auto function,

The automatic air conditioning will achieve optimal operation if "cooling with air dehumidification" is also activated. If necessary, cooling with air dehumidification can be deactivated.

cooling with air dehumidification is the A/C button on which Mercedes quote,

The "cooling with dehumidification" function is only available when the engine is running. The air inside the vehicle is cooled and dehumidified according to the temperature selected. This prevents the windows from misting up.
Risk of accident

If the "cooling with air dehumidification" function is deactivated, the air inside the vehicle will not be cooled (during warm weather) or dehumidified. The windows could mist up more quickly. This may prevent you from observing the traffic conditions, thereby causing an accident.

So, if A/C light is off, then air con is off too.

Russ

 

[Miffy]

In the wet days I tend to run it on auto with the a/c on.

you mean you have a few dry days?

I have not yet managed to visit your wonderful place without the rain

 

[survey]

This is what Mercedes say about the auto function,

The automatic air conditioning will achieve optimal operation if "cooling with air dehumidification" is also activated. If necessary, cooling with air dehumidification can be deactivated.

cooling with air dehumidification is the A/C button on which Mercedes quote,

The "cooling with dehumidification" function is only available when the engine is running. The air inside the vehicle is cooled and dehumidified according to the temperature selected. This prevents the windows from misting up.
Risk of accident

If the "cooling with air dehumidification" function is deactivated, the air inside the vehicle will not be cooled (during warm weather) or dehumidified. The windows could mist up more quickly. This may prevent you from observing the traffic conditions, thereby causing an accident.

So, if A/C light is off, then air con is off too.

Russ

Thanks Russ. So Auto does NOT override the A/C light function and effect comfort cooling. To get any temperature in the cabin less than ambient temperature on the Auto function, the A/C light HAS ALSO to also be lit.

Would this also mean that the compressor is switched in and out by the Auto function OR as a previous poster said - if the A/C light is lit - it is ON and compressor running. I always thought climate control switched the compressor in or out as necessary.

 

[rf065]

Thanks Russ. So Auto does NOT override the A/C light function and effect comfort cooling. To get any temperature in the cabin less than ambient temperature on the Auto function, the A/C light HAS ALSO to also be lit.

Would this also mean that the compressor is switched in and out by the Auto function OR as a previous poster said - if the A/C light is lit - it is ON and compressor running. I always thought climate control switched the compressor in or out as necessary.

If the A/C light is off, the compressor cannot run.
If the A/C light is on, the compressor is on, but it cycles off & on depending on how much cooling is required.

Russ

 

[LSD]

To get any temperature in the cabin less than ambient temperature on the Auto function, the A/C light HAS ALSO to also be lit.

Not necessarily. The air being blown into the cabin has been slightly compressed and accelerated through the system by the blower, there is a pressure drop as it expands into the vents and then the interior, so this air can be cooler than outside air, more so the cooler the day. Some vehicles can cool very well without the air con. to a point.

As to the original question... I've never yet seen a climate control system where the auto setting fully overrides the main air con. on-off switch. As said, in older Mercedes it sort of operated in that way by default: the air con was on unless the light was lit, which indicated "Economy" mode.

 

[MSG2004]

This is what Mercedes say about the auto function,

The automatic air conditioning will achieve optimal operation if "cooling with air dehumidification" is also activated. If necessary, cooling with air dehumidification can be deactivated.

cooling with air dehumidification is the A/C button on which Mercedes quote,

The "cooling with dehumidification" function is only available when the engine is running. The air inside the vehicle is cooled and dehumidified according to the temperature selected. This prevents the windows from misting up.
Risk of accident

If the "cooling with air dehumidification" function is deactivated, the air inside the vehicle will not be cooled (during warm weather) or dehumidified. The windows could mist up more quickly. This may prevent you from observing the traffic conditions, thereby causing an accident.

So, if A/C light is off, then air con is off too.

Russ

On my previous W203,a 53 plate clasic se - the climate control was OFF when the light was {{{on]]]]] = a lady at work had a 51 plate 'A' class and she sked e about the 'air-con' was getting hotter when she turned it on, ie the red light came on - I told her that it was actually off, problem sovled

 

[survey]

rf065 and LSD - I think we are all singing from the same hymn sheet now.

LSD - your reasoning explains why I felt that the cooling was working with the Auto ON but the A/C light OFF.

Realistically then, the A/C light does need to be ON when the Climate Control is set to AUTO to achieve real cooling. And from what you say with the A/C light ON, the compressor WILL indeed cycle in and out as required by the cooling temperature set.

 

[LSD]

Realistically then, the A/C light does need to be ON when the Climate Control is set to AUTO to achieve real cooling. And from what you say with the A/C light ON, the compressor WILL indeed cycle in and out as required by the cooling temperature set.

That's right. Climate Control will do all it can to automatically maintain the cabin at the selected temperature with what's available to it, heater, blower, air con., choice of air outlets. It can only cool to a point though until the air con. is avaliable to it by being switched on. It will then cycle it on & off as needed as you say.

If the air con. is switched on but CC is off, then it will just continually operate as you've set it, i.e., it's in a manual mode, so the flow and where the flow is from stays as you've set it. (note: the compressor may still cycle on & off when used like this. The system itself within the engine bay has thermostatic controls independant of the car's interior, and will run itself only enough to provide the maximum design cooling output and dehumidification).

 

[duquesa]

After reading all the posts I am baffled,In future if it is to hot I will open the windows,and if cold shut them
Ken

 

[survey]

After reading all the posts I am baffled,In future if it is to hot I will open the windows,and if cold shut them
Ken

I believe that rf065 and LSD have defined matters. Thanks chaps. I just hope that nobody comes up with another answer to confuse things!

 

[rf065]

After reading all the posts I am baffled,In future if it is to hot I will open the windows,and if cold shut them
Ken

Why complicate things, just set the temperature & leave it on auto all the time. Then you do not have to do anything.

Russ

 

[survey]

Why complicate things, just set the temperature & leave it on auto all the time. Then you do not have to do anything.

Russ

Except ensure that the A/C button is in the ON position if you want cooling to operate with the Auto function!

 

[rf065]

Except ensure that the A/C button is in the ON position if you want cooling to operate with the Auto function!

But I never turn it off. :lol:

Russ

 

[survey]

But I never turn it off. :lol:

Russ

Fair enough!!!:lol:

 

[*Thumper]

It is going to be fun here soon when some say that the light must be off and others on

Did'nt take long did it ..............

203's, 204, .......on my old merc ......... back in the day ..... and a simple thread goes to Timbuktoo and back ............... love it !

I'll wait a couple of pages, then ad the simplest of explaination ...although 1 or 2 have tried ...........and been completely ignored ..........