CLS Misting up

[SilverSaloon]

i've been steaming up over the last few weeks. aircon now on a lot more than usual. dark, cold, wet nights are to blame.

 

[AntJC]

The ambient temperature control is there to protect the system from freezing up. Hold one of the AC pipes with the system running and you will soon see why it’s there (the refrigerant always circulates cold).

If it was not there you could end up with a frozen pipe or union, with the compressor still running causing the overall system pressure to exceeding safe working pressures leading to a ruptured pipe/union or pump or self destructing condenser!!

Antony

 

[whitenemesis]

In both my W203 and wifey's new Honda Jazz it's been impossible to turn the a/c for the last few weeks.

There is something curious about the Merc system in that you can turn it off and the windows stay clear but then suddenly mist up a few mins later.

A comment in another thread from an indie indicated that on a car he was working on the a/c compressor clutch stayed partially engaged when the a/c is turned off. The percentage of engagement can be changed using Star.

If this is the standard way the system works it would certainly explain what's happening in my car. On Mrs R's Jazz, turn the a/c off and the car just instantly steams up.

This is because there is a delayed shutdown of the compressor

 

[alexander patie]

indeed, when is the acoff not off? when you are driving a merc! it will shut down slowly to avoid the misting you would get if it stopped abruptly. i suggest it takes a good few minutes to do this, running at 30% immediately you turn the acoff, then dropping.

 

[Ajenks]

Why are you switching the air con off?
Mine is on permanent, it is climate control so let it do its job and leave it on.

Russ

Hey Russ I'm new to climate control, seriously do you leave it on all the time? I have a clk and it says AC on the switch is this climate or aircon?

 

[Rory]

Agreed that there is no substitute for de-humidified air, but don't forget that most AC compressors will not engage when the external ambient temperature falls below +5c.

It's typically 3C and I've certainly been in trouble on start-up when the previously wet evaporator has dumped moisture into the car but the a/c hasn't worked.

Once it's below freezing then humidity is much lower so it's not an issue.

 

[Rory]

This is because there is a delayed shutdown of the compressor

This is a pain as you can't do the "trick" of turning the a/c off a couple of miles from home to dry out the evaporator. I hate leaving it wet as it harbours bugs, and, as mentioned above it can potentially cause problems if the temp is hovering above freezing when you next use the car.

 

[whitenemesis]

I've run mine now for 4yrs, permanently on, no problems, no nasty smells, no misting windows.

It's designed to run 100% of the time, leave it alone!

 

[EDZ649]

The reason cars steam up is that they are so air tight, no natural air circulation.

Leaving the a/c on is the only way to make sure the air in the cabin changes enough times to reduce the amount of moisture in the air. Remember, condensation will form on the coldest surface and that is usually the glass.

 

[rf065]

Hey Russ I'm new to climate control, seriously do you leave it on all the time? I have a clk and it says AC on the switch is this climate or aircon?

The air con gas also carries a lubricant around the system, if you do not use it, the joints will eventually leak meaning costly repairs if you want it fixed.

I've got my CLK up to 59.1MPG and switched the air con off to try to reach 60MPG, but it did not make any difference. Seriously, when on or off I cannot tell the difference in MPG.

I cannot find any downside to leaving it on all the time, but switching it off, steams up the windows.

If you have air con, it is simply a button on or off and everything else is done manually. If you set the temp & the car cycles the air con on and off, and directs it to whatever vents are required, that is climate control.

Russ

 

[alexander patie]

this will always devide opinion, but i too would leave the aircon 'on'. it will make very little difference to mpg in winter. the reason we buy these marvelous cars is so we don't have to worry about heating/cooling/misting, just leave it to the expensive control unit and complex parts, no?

 

[Simon_M]

Yep, leave the aircon on all the time, unless I have the windows open in summer.

 

[rothbury]

Yep, leave the aircon on all the time, unless I have the windows open in summer.

Interesting thread! As some others have said leave the climate control on - I did for 4 years in my W211 E 320i and though occasonally I switched it off it didn't seem to affect the fuel consumption.
What I HAVE found in the W204 250 cdi is that the problem arises when you go out for a meal for instance come back to the car a couple of hours later and all the windows are dripping with condensation so it's impossible to drive offf for a few minutes! This has been admittedly over the last few very damp weeks.The Merc salesman said "they all do that sir" but I've never had a car do it so badly before. The idea of opening both front windows and turning the heating down a few minutes before stopping doesn't really appeal!
But seriously is it because they are really well sealed or what??

 

[Baron_Samedi]

If the car is sealed, there is something wrong... there are vents specifically to equalise the air pressure in the car.

 

[steve_w]

There's a long thread about this here: Google Translate

It seems there's an "afterblow function" designed to dry the evaporator. It can be switched off with Star.

 

[Noodle-Pulp]

A good cheap anti-fogging solution (used by many scuba divers) is peel a potato and use it on the windows...

 

[Baron_Samedi]

as opposed to...

And don't even go there, mister....

 

[rothbury]

There's a long thread about this here: Google Translate

It seems there's an "afterblow function" designed to dry the evaporator. It can be switched off with Star.

with what??

 

[Baron_Samedi]

with what??

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

 

[rothbury]

There's a long thread about this here: Google Translate

It seems there's an "afterblow function" designed to dry the evaporator. It can be switched off with Star.

That link leads to a classic selection of badly translated posts which are HILARIOUS!