CLS Misting up

[rothbury]

Time for you to check out forum search... STAR...

Why bother to reply??

 

[Rory]

with what??

StarDiagnose is the "tool" (laptop based diagnostic software) that MB dealers and independants use when working on the cars.

However many of the functions are very buried and I doubt the average MB mechanic would be able to find something like this, unless there's a bulletin from Mercedes to explain how to do it.

The whole idea of an "afterblow" type function seems stupid - why leave the car full of wet air?

Anyway, my W203 mists up too, and that doesn't have this afterblow function.

 

[yachtman]

I have been the proud owner of a 2007 cls 320 fro 6 weeks now,i love the car but cannot stop the windows steaming up unless i leave the aircon on ,the dealer said its coz the windows are high anyone with the same problem or does it need to go into mb,by the way its 2 zone

For what it is worth I would check the drains are clear from the heater inlet area, dont know about your model, but frequently are rubber balls on rubber pipes in the engine bay at the bulkhead.

equally, I was told (while on a road test with service manager at my local dealer Drayton Stafford) if the air con has been on even when turned off by pressing the auto switch, the aircon remains on to stop a fog over as the condenser thaws.The way to turn off fully was to turn off the fan manually as well. This applied to my c sport, & checked out on feeling pipes etc later at home.

Others will tell you if this applies to the cls as well

 

[Rory]

For what it is worth I would check the drains are clear from the heater inlet area, dont know about your model, but frequently are rubber balls on rubber pipes in the engine bay at the bulkhead.

equally, I was told (while on a road test with service manager at my local dealer Drayton Stafford) if the air con has been on even when turned off by pressing the auto switch, the aircon remains on to stop a fog over as the condenser thaws.The way to turn off fully was to turn off the fan manually as well. This applied to my c sport, & checked out on feeling pipes etc later at home.

Others will tell you if this applies to the cls as well

I think that's nearly right. Pressing the auto button won't turn the a/c off at all - pressing the EC button turns it off, but seems, as you suggest, to leave it partially engaged for a while to stop the car suddenly misting up.

The cold air in the car comes from the evaporator - the condensor is attached to the main radiator at the front. The evaporator shouldn't freeze - that's why a/c in cars doesn't work below about 3C - but it will get very wet. It's this wetness that would blow through into the car as the evaporator warms up when the a/c is shut off

 

[cplnoonoo]

So reading all of this thread there isnt really a straight answer to this...looks best to leave it switched on but turn off every so often, turn on all the time, dont use at all, use a little bit. Which one lol?

On my c180 w203 coupe i have the auto button on most of the time so i can keep the car at a certain temp and the windows dont seem to mist up much and the llittle red light (i kno oh so technical) on the a/c button is on which the manual says means the air con is turned off so how come my windows dont mist up if the air con is turned off?

 

[Benzowner]

This has been a good read but no one has really said why cars mist up. The reason cars mist up is because one or more organic lumps enter the car breathing out warm moist air that when it hits a cold surface condensates and the larger the volume of air in the car, the more moisture can be held in suspense. When the organic steam breathing lumps then leave the car, it cools and the moisture condensates on all the surfaces. Over a period of time this can lead to damp inside the vehicle which when warmed up by the sun can cause misting on the windows. The only cure is to dry the car out usually by leaving doors open on sunny days. The reason car dealers leave hatch back up on their cars. To reduce the effects of condensation, leave the air con on as others have said

 

[Voltman]

Just to add to this debate, Mercedes are aware of a problem with Cls misting up when the aircon is switched off. The dealer has told me they have had a lot of complaints about this problem. My car is currently at the dealers having this problem looked at. I have driven many Mercedes over the years & my Cls is the first one which has got this problem. My last 3 S class's could be driven without aircon on & no misting up or maybe a little in very humid conditions. I will post back when i pick the car up later. As a side note they have told me they are doing various software updates which will take 2.5hours!!

 

[Rory]

On my c180 w203 coupe i have the auto button on most of the time so i can keep the car at a certain temp and the windows dont seem to mist up much and the llittle red light (i kno oh so technical) on the a/c button is on which the manual says means the air con is turned off so how come my windows dont mist up if the air con is turned off?

Are you sure the light on the a/c button means it's off? MB have messed around with that indicator over the years.

I generally drive with my a/c off unless it's too hot. The problem arises if you turn it on at this time of year then it's impossible to turn it off again - the car just mists up once the a/c compressor has gone through its run-down cycle (takes a few mins).

 

[Rory]

As a side note they have told me they are doing various software updates which will take 2.5hours!!

What's the betting they'll fix it by leaving the a/c partially engaged all the time!

Software updates always take ages - the dealers hate doing them.

 

[Voltman]

What's the betting they'll fix it by leaving the a/c partially engaged all the time!

Software updates always take ages - the dealers hate doing them.

 

[Sp!ke]

Wondering if the pollen filter is past its best or perhaps even damp.

Might be worth having a look anyway.

 

[yachtman]

I think that's nearly right. Pressing the auto button won't turn the a/c off at all - pressing the EC button turns it off, but seems, as you suggest, to leave it partially engaged for a while to stop the car suddenly misting up.

The cold air in the car comes from the evaporator - the condensor is attached to the main radiator at the front. The evaporator shouldn't freeze - that's why a/c in cars doesn't work below about 3C - but it will get very wet. It's this wetness that would blow through into the car as the evaporator warms up when the a/c is shut off

Rory

Thanks for the very polite correction re evap & condensor, momentary brain fart,on my part. I must not reply to posts after 12 hour shifts!!!

 

[karozza]

What the dealer could have explained is that the CLS has a more inclined windscreen (not higher) which can trap more mist than a more vertical screen. Most probably the same reason between the 203 & 210.

A good glass clean really does help but after that nothing beats the A/C

 

[cplnoonoo]

Are you sure the light on the a/c button means it's off? MB have messed around with that indicator over the years.

I generally drive with my a/c off unless it's too hot. The problem arises if you turn it on at this time of year then it's impossible to turn it off again - the car just mists up once the a/c compressor has gone through its run-down cycle (takes a few mins).

Yes the button even says A/C off. the manual also says that when the light is illuminated that the air con is off. Im wondering if this is the same idea to the ESP lamp on the instrument cluster in that if the ESP is not meant to be off then the symbol will be illiuminated? Could be that the air con is not meant to be off when the auto is on so it lights up. Also noticed that even when not in auto mode and just manually controlling fan speeds the light comes on as soon as the fan is turned on at the lowest setting.

 

[Rory]

Yes the button even says A/C off. the manual also says that when the light is illuminated that the air con is off. Im wondering if this is the same idea to the ESP lamp on the instrument cluster in that if the ESP is not meant to be off then the symbol will be illiuminated? Could be that the air con is not meant to be off when the auto is on so it lights up. Also noticed that even when not in auto mode and just manually controlling fan speeds the light comes on as soon as the fan is turned on at the lowest setting.

The light in mine is on when a/c is off! But, as mentioned earlier, MB have changed the orientation of the light over the years. I think the auto indication is worse - red lamp on when auto is on. Seems odd having a red (ie warning) lamp showing for what is the normal operation.

I think in most, or even all, cars, the a/c goes off when you turn the fan off - I presume this is to stop the evaporator freezing without air passing through it.

 

[Voltman]

Just to add to this debate, Mercedes are aware of a problem with Cls misting up when the aircon is switched off. The dealer has told me they have had a lot of complaints about this problem. My car is currently at the dealers having this problem looked at. I have driven many Mercedes over the years & my Cls is the first one which has got this problem. My last 3 S class's could be driven without aircon on & no misting up or maybe a little in very humid conditions. I will post back when i pick the car up later. As a side note they have told me they are doing various software updates which will take 2.5hours!!

Car still not back yet as they have found other faults (Comand wont play Dvds now). Will update on the misting problem hopefully tomorrow.

 

[cplnoonoo]

The light in mine is on when a/c is off! But, as mentioned earlier, MB have changed the orientation of the light over the years. I think the auto indication is worse - red lamp on when auto is on. Seems odd having a red (ie warning) lamp showing for what is the normal operation.

I think in most, or even all, cars, the a/c goes off when you turn the fan off - I presume this is to stop the evaporator freezing without air passing through it.

Yes, as i said the a/c light stays ON when a/c OFF and the light on auto stays ON when auto is turned ON. if i turn auto OFF then the a/c light goes OFF but this still means that the a/c is OFF as the whole heating system is not in operation. if i leave auto OFF and manually turn the fan speed up 1 notch from zero then the a/c light comes ON indicating that the a/c is OFF lol. Does that make any sense lol?

 

[Rory]

Yes, as i said the a/c light stays ON when a/c OFF and the light on auto stays ON when auto is turned ON. if i turn auto OFF then the a/c light goes OFF but this still means that the a/c is OFF as the whole heating system is not in operation. if i leave auto OFF and manually turn the fan speed up 1 notch from zero then the a/c light comes ON indicating that the a/c is OFF lol. Does that make any sense lol?

Yep.

Don't know why you'd turn the fan to zero though - I leave mine on 3 or 4 to blow some air through whenever I switch auto off.
I think one of the issues with the auto setting is that, once at set temp, the fan blows too slowly so the car can get a bit stuffy.

 

[soley]

Car still not back yet as they have found other faults (Comand wont play Dvds now). Will update on the misting problem hopefully tomorrow.

interested to hear how you get on

 

[Simon_M]

OK, OK, what have you done?

This week my CLS has been misting up, not while in use (with a/c on all the time) but when parked up. If I drive it for a while, park up and within an hour it has misted up. Same overnight.

Last time a car did this it was a VW PAssat that had about 100Litres of water in the rear footwell.

I have checked all carpets and they are dry - didn't do this last year...

S