AC Problem, Newbie Here

Hi
Have you tried the 2 Red & Blue Buttons on your upper Dash ,the blue for cold & red for hot ,they activate something under there and i noticed on my 500 that it has to do with the outer airoutlets , defentitely something there , your main Control may needs to b changed or has a contact somewhere ,old fashion try ,give it a good Wack on the side ,it workt for me ,the duovalve on my 500 is under the location on the Pic,u can't miss it .
Ciao
When u turn the Aircon on make sure u dont press EC or any other button , test ,Press Auto plus turn the wheel all the way to the blue section until u feel the click ,when it's on, tap the button you want it on several times until the red light on that specific button turns on it may fixes itself sometimes .

samosali said:

defrost is built to blow a hot air and only a hot air. nothing but a hot air.

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Yes , true ,but it only comes out from the Top for the fast Windscreen Defrosting,it has nothing to do with the other Vents outlets or buttons ,there is only 1 for that anyway .
Ciao

Sounds like you have discover'd yet another hidden Talent within the W140,i have never tried that yet Aircon on & Windscreen Defrost on , i will check this out but you do sound right already 2 me , the Car was build like it .

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it is very simple to understand:

- in most cars (if not in all cars) first the outside air is cooled by AC core which produces cold air (because of gas expansion inside the core). But the temperature of the produced cold air is ca. +6 °C .... not - 40°C in this stage the moisture of the air is also reduced because cold air cannot contain so much water than hot air.

- if the AC is put OFF then the outside air is not cooled and it passes through heater core which increases its temperature to let's say +40 °C but this is only for example ... the system then heats the cabin with this warm air.

I think you are bothered with the wrong assumption that cooling and hating are not working together but this is very wrong, because they do. explanation is very simple: when AC works on maximal power it produces +6 °C but as you know the cars are designed to increase the outside temperatures from - 30°C (for instance) to inside temperature +30 °C. so the heater core in the car does not know if it receives

a)the direct outside air with temperature let's say -10°C or
b)the air cooled by AC with temperature 6 °C like I stated.

So the path of the air is:

outside air - AC core - heater core - cabin - way out(the effect of AC when turned ON means nothing to heater in terms of heat, the heater can heat the cooled air without any problem ... but anyway, it is ok to have AC on to reduce the moisture)

I hope it is clear now . trust me, I have built-in once a complete AC device into another car and it worked. I was forced to study how the thing works.


P.S.: there is a big difference between good and bad AC devices: in bad cars the AC cannot function if outside temperature is below +5°C which means that you will have foggy windows, ecpecially if there is raining. In a good car, like MB, AC will work also at lower temperatures and therefore it will reduce the content of water in the cabin air, so the windows will not be foggy.I never turn my AC off. first because of the above facts and second because i believe it is better for an AC system to be constantly in move.

dave perth said:

personally, i think u will be very very sorry u bought that car mate, sure they look fantastic, no argument there, the bodywork is pretty good also , but the bits that makes these cars, ie all the electronic gizmos, and gadgetry , are purely an absolute disasterous nightmare, as the reliability is atrocious. i am going to collate a list for the forum of all the pieces that have failed to date on my car, i will be purchasing a new quality vehicle in the near future, hyundai getz, and i have absolutely no doubt that when its the same age as my 400 is no where near as many bits will have needed to be replaced . !

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Hi
Please dont take no offence Dave but the Car you bought must have been a one of Lemon or maybe misstreated by the previous owner (neglected due to the cost of Parts ) My Car is a Perfect example of the w140Quality,absolutely & always 100% ,everythink works & i'am sure that there are many many still out there just like it ,these days People r only out to look for bargains ,cheap cheap cheap and then they complain later ,who cops it ,in our case the poor W140 ,these cars are not for everyone ,a lot of people want them and when they have it and something does brake down they replace it with cheap aftermarket Parts because they cant pay for the real thing,would u pay for example ,Wiper relay $195 2nd hand or $450 new ,i choose the $450 1 so i dont pay twice 4 it & i know it will work for years to come. I do have 3 other cars made in Japan and yes they are ok for in the city but are nowhere near the Quality of this Car ,my Car is a 93 Model & it looks as if it came out of the Factory yesterday when it's all cleaned up ,i dont think that a Hyunday will look that good after 5 Years with 180,000 Km on it ,that is ,if it will make the 100,000Km mark 1st, our cars S500/600 r just running in at that if they have been Serviced etc...,i recently had a 2500Km trip with my S500 & it dident want to stop not even for Petrol ,it loved the Highway so much that when i was finally back i too wanted to go again , the Car dident feel all those Km at all , as if i wend around the block .
How long have you had the w140 for anyway to give you this bad impression on it ?
Ciao:thumbsup: