The A/C button lights up red when it is on so I don't think one will miss it. By default it should be off all the time. If not you'll be using a lot of gas.

 

As jtcb mentioned, AC button when pressed lights up red and when its on it consumes more gas. Even without the A/C button pressed the auto climate control does a good job in supplying cooler or warm air when needed in my 2009 B. Thats all i have used so far, never had the A/C on.

 

The AC compressor works when you turn the temp up, I do it all the time, it keeps the interior dehumidified.

Run your AC at least once a month for a couple of minutes to lubricate the bearings and prevent the seals from drying out.

Haven’t run the AC yet???? It is so hot here that rarely don’t run the AC.

 

Thanks for your replies.... Yes it's very hot, and we've been using the A/C all the time. I was just wondering for the upcoming rainy fall season and winter weather.

But it's interesting that you are able to run the A/C and turning the heat up to keep things dehumidified. I assume your fuel consumption will be higher if you do this. Is there any other negative impacts for running the A/C and turning up the heat?

 

The salesman recommended that the A/C switch be turned on all the time. Kind of a waste when driving with the roof open however.

Bill

 

Yeah it ought to be run once every couple of weeks for ten+ minutes, but off when it's not needed.

 

i keep the sunroof open and thats all we ever need in halifax even in the hottest days. Only when the road noise gets too much with roof open on highways i have to close them. Ya, halifax, NS doesn't get too hot, it gets over 25 deg c very rarely. i will keep it on once in a while as suggested.

 

I think some members are reffering to different model year cars so I will try and explain...

The original A & Bs had a A/C OFF button which would light up red when A/C is turned off

The newer A & Bs have a A/C button that lights up red when A/C is on

In general its good practice to leave A/C turned on all year round or at least once or twice a week to keep the system clean and operational

 

In general its good practice to leave A/C turned on all year round or at least once or twice a week to keep the system clean and operational

Hi J400uk,

Thanks for posting those pics. Since you say it's good practice to leave the A/C turned on all year around...do you foresee any problems with leaving the A/C on, and turning up the heat during the winter months? I'm still wondering if this will cause any harm to the heating / cooling system. Someone here mentioned that leaving the A/C on and turning up the heat will keep the air dehumidified and keeping us warm. What are your thoughts?

Andy

 

J400uk explained it well with those pics. My 06 has the A/C red light ON when not in use.

DEVOURS

 

J400uk explained it well with those pics. My 06 has the A/C red light ON when not in use.

When I got the car a few years ago, the A/C would only come on when the fan is turned on and when the A/C button is pressed and it would light up red. But recently, I am having a strange behaviour. The A/C comes on when I turn the fan to ON and I can sense the compressor engaging. Pressing the A/C button to ON/OFF is not making any difference, the A/C remains ON.

In effect the A/C comes on when I turn the fan to ON.

 

So did my original 05 B, my newer one 07 works the other way round (light on a/c on).

 

Mine is also lights on when on.

 

Turning the A/C off before parking the car for a day or two is a good idea, to avoid moldy smells when starting the car up the next time.

 

I always try (note try) to turn the A/C off a few blocks from home and let some of the water evaporate from the evaporator (no pun intended) to try to stop mold from growing. On a very hot day I think removing a load from the engine prior to turning it off also helps in stabilizing temperature.

Strange about the lights on the first cars being on when the A/C is off, but I guess it makes it easier to find on a dark hot night

Bill

 

On the 2008 model the light is out when the A/C is off.

 

same with 2009, light is on when A/C is on and off otherwise

 

If you select defrost, even if the ac is selected OFF you will get ac assisting to dehumidify.

 

So does the A/C light come on again when defrosting in your car? I do not recall this function in mine, also a 2008 model. I know US domestic cars do this but I've never seen a European one that did it.

 

On most cars the AC compressor turns on when the defroster is turned on. It makes sense when you know how the AC works on a car.

Turning off the AC before turning off the engine is one way to hopefully alleviate the problem of mildew build up and smell but I rarely remember to do that. Another is to turn up the heat before turning off the engine; this supposedly dries out the evaporator as well. I did this a few times the last time the stink started and haven’t had the problem since. However with temps like we’ve been having here, 38 - 41° :crybaby2:, everything dries quickly so there are very few smelly problems to contend with.

With my last car I didn’t use the AC with higher temps at first but I had heard that it was a way to quickly dehumidify the cabin and keep it dry, so one cool damp evening while driving with several people in the car I tried it and it worked very well so that is why I’ve continued to do this. We do that same thing when we go to places that are actually cold in the winter as well . I'm just telling you why I do it not that you should do it.

Air Conditioning - How Does A/C Work - Automotive Air Conditioning Description

How Does a Car Air Conditioner Work? | eHow.com

HowStuffWorks "Windows down or A/C on -- which is more fuel-efficient?"

 

From the ML Operator’s Manual:

The automatic climate control system switches to the following automatically:

• Most efficient blower speed and heating power, depending on outside temperature
• Air flows onto the windshield and the front door windows (side air vents must be open)
• The air conditioning compressor switches on at outside temperature above approximately 41°F (5°C) for air-drying.

The air conditioning compressor remain on even if the indicator lamp in button [MAX] goes out. This helps to prevent the windshield from fogging.

-----------------------------------------------------------------------------------
From the B Operator’s Manual:

Warning! – Fogged windows impair visibility, endangering you and others. If the windows begin to fog on the inside, switching off the air recirculation mode immediately should clear interior window fogging. If the interior window fogging persist, make sure the air conditioning is activated.

The cooling function, only operational when the engine is running, cools the vehicle interior down to the selected temperature. The cooling function also dehumidifies the air in the vehicle interior, thus preventing the windows from fogging.

 

From the ML Operator’s Manual:

The automatic climate control system switches to the following automatically:

• Most efficient blower speed and heating power, depending on outside temperature
• Air flows onto the windshield and the front door windows (side air vents must be open)
• The air conditioning compressor switches on at outside temperature above approximately 41°F (5°C) for air-drying.

The air conditioning compressor remain on even if the indicator lamp in button [MAX] goes out. This helps to prevent the windshield from fogging.

-----------------------------------------------------------------------------------

I wish that the B had a full auto system. Our SAAB also varies the air speed when heating or cooling but never gives any indication if the compressor is running.

Bill

 

That's not surprising, the ML is a Domestic built truck

 

And that means...??? Last time I checked Mercedes is a European brand.

I wish that the B had a full auto system. Our SAAB also varies the air speed when heating or cooling but never gives any indication if the compressor is running.

Bill

Isn't that system available on the 2009 model year B?

Full auto systems are fine until they fail after ten years, then you have nothing! Been there done that.

Oh, you must be referring to one of those French cars.

 

Full auto systems are fine until they fail after ten years, then you have nothing! Been there done that.

 

"Isn't that system available on the 2009 model year B?"

Yes it does

 

I guess most of us have to be content :crybaby2: with semi automatic temperature control. It does beat a sliding lever or a rotary knob:thumbsup:

Predicting humidex numbers of 43 C this week so I think there may be more interest in cooling on the West Coast of Canada.

CA-B200 you must be our resident A/C expert any tips???


Bill

The 43 is a plus number and not the minus that many Canadians suffer with part of the year

 

Nadine

Does the ML go into recir mode when the A/C is on? Our SAAB goes into recir after a minute when in cooling mode. The B will not stay in recir mode and it seems much more efficient to cool cabin air than bring in 100% hot outside air all the time.

Bill

 

I don’t know if the recirculation mode comes on automatically in the ML. I didn’t like using the AC in the auto mode but my husband did and he thinks that it go into recir mode and like the E when it goes into the recir mode automatically the light does not turn on.

It’s not just the B that the recirculation button will not stay on for ever it is dependent on the length of time and inside/outside temps. The automatic systems don’t seem to be as forgiving as the manual systems but with the automatic system in the E-class the recirc mode will automatically turn on if the outside temps are high and or when CO and NOx levels are high such as in a tunnel. I can’t see why this wouldn’t be the case on all the new automatic systems.

The interior on a car with a sunroof fitted with only a solar shade is going to get hotter faster despite the color of the car so block some of that. Depending on where I leave the car I pop the first panel just a bit and I have a sun shield slipped in-between the roof and sunshield. Well, now that it’s stinking hot all the time I leave that sunshield there during daylight hours.

The majority of solar heat gain is really through the glass, yes there are studies to support this. Metal skin temps were reduced with the cool paint technology on the car roofs but that “did not have a significant impact on interior temperatures”.

Soon there will be new regulations in California that require windshields to reflect at least 30% of solar energy, side and back glass at least 42% and sunroofs 65%. Mercedes and BMW uses some of the technology now available to reduce solar heat gain, if you look carefully at the windshield of the cars with this metallic glazing you will see small squares in certain parts to allow the use of portable devices such as GPS and toll road transponders.

I had a 99% blocking UV ceramic film put on the windshield and front side windows, this does make a huge difference but the majority of the heat comes through the sunroof. Do not put any kind of window film on the panorama roof; window film is only for glass not plastic.

 

Nadine who is the foxy lady in your avatar?? DEVOURS has the raccoon and the Bee has been done so what animal is next?

Bill

 

Nadine

That country side looks so interesting and you do have an eye for great photos:thumbsup: She may be a good mascot to bring along to a Duck's game, because I can not see her lasting long out in that hot sun, especially without A/C
Secondary highways and roads are where you see the real America or at least your independent spirit.

Bill

 

Nadine
That country side looks so interesting and you do have an eye for great photos:thumbsup: She may be a good mascot to bring along to a Duck's game, because I can not see her lasting long out in that hot sun, especially without A/C
Secondary highways and roads are where you see the real America or at least your independent spirit.
Bill

Thanks Bill, hwy 395 can be a fun road, it’s so varied and interesting. I hope you two enjoy the drive. The southern part can still be quite hot during daylight hours in early autumn so make sure your AC is working.

I’ll have my camera ready for my next avatar some time this fall. GO DUCKS!