starbrite

MY 2004 manual states that air recirculation is activated when the A/C is turned on.
I've never found the A/C particularly cold in my car and the other day noticed (yea, I never looked before) that the light was OFF (little car outline w/the loop arrow).
So, obviously outside air was coming in.

Turned the sw ON and low and behold, nice COLD air. In fact I also tried turning the sw on w/the A/C off.
Guess what, turning the A/C on deactivated the sw.

I don't know if this is peculiar to my car or year but the point of this post is that you should check that when you turn on the A/C, check that the recirculation light is on.

Clinton Horn

I live in Atlanta and I would venture to guess that our black 320 gets hotter than any color car in NY. I know you have some hot days but our humidity is fierce and I have been told that diminishes the AC performance as well.
If you are not getting comfortable with outside air, you may have a low 134 charge. I have other vehicles that do about as well but I will say that when the auto button is on and those fans go into giddy up mode, at least I feel that relief is on the way. They are so loud, people actually stare at the hood as if they expect the thing to fly. I have no complaints about cold air.

Barry45RPM

I've never seen the recirc light on unless I turn it on. (on my '04, or on my 07 which has slightly different set of buttons & display) You should open all the windows & roof with the key as you enter, start the car, press MAX (if you're in a hurry for cold air fast) and drive with the windows down for at least a minute or two, then close everything.. (I do). I would also have them check for low refrigerant. My '04 had good, cold, fast A/C. My '07 was delivered with not enough refrigerant & couldnt keep up my 1st springtime with it till I got fed up & brought it in. Its been good since then.

mcleantmw

You should check your owner's manual to verify this or check with your MB Dealer.......but you don't have to use the Recirculated Air setting for your A/C system to work.........same goes for the heater. My A/C and heater work fine without using the recirculated air setting. That feature, I recall, is used primarily to get your heater to heat up faster in really cold weather.........recirculates the inside air through the heater instead of using the very cold outside air. Could get kind of stale air just recirculating the old air in your vehicle.......similar to the airliners with all the passengers' breathing the contaiminated air from each other! In fact, sometimes when I fly on an airplane on a five plus hour tirep I get a cold afterwards from the sick air.......flew back from 7.5 hour Paris flight last May and then got a bad cold.

starbrite

Of course I checked the manual first, that's why I made the op. Page 191 to be specific, when operating the A/C "air recirculation comes on automatically at outside temperatures above 41 degrees F."

@Clinton/Barry...yes, refrigerant level is OK. Barry,If both your cars did/do the same thing, then it must be a printing error.

BTW Clinton, I know your weather well. I spent 53 weeks in Valdosta, GA, back in '65. You're right, it can be brutal in the summer.

Roehl

How would you know if your refrigerant level is low? On the AC panel you can check the refrigerant pressure and mine show I have 10. My AC is not that cold compare to my other car.

Recirculation button is OFF by default on the 04. It closes when the outside temperature is above 74deg but the light doesn't lit on.

Clinton Horn

A "rule of thumb" for 134 and r-22 (home) is 18 to 21 degrees temp drop from cabin (room) temp to discharge air. IE if the cabin temp is 80 the discharge should be AROUND 60 degrees. All of the mechanical engineers can start flaming now. This does not account for relative humidity, dry bulb temp etc. but it is a reasonable guide. If you are pulling in 90 degree outside air by using the fresh air intake, you need to subtract from that temp. so your discharge will be 70 degrees. This works down to the limit on A-C which I think is about 54-55 degrees. Obviously if you start a black car in the sun on a 95 degree day and let it idle, your readings will be less than stellar. You can buy a vacuum gauge that fits on the SUCTION hose Schrader valve and get an idea if it is within the acceptable range. They come in a variety of flavors and start about 15 bucks. IF you are going to brave charging the system, you can damage lots of stuff by OVERCHARGING. If you don't get enough gas in the system it simply does not cool effectively. I have never added compressor oil but that is another area best left to knowledgeable people. Unless you have a leak, my experience has been about 10 years before enough gas escapes to cause any noticeable difference.

Tjdehya

Airplanes don’t use recalculated air. It uses the very cold outside air mixed with hot bleed air from the engines. The stale air you speak of is just from 200+ people stuffed in a tube, not from recalculated air.

When I read the manual it said recirculation is always off unless you select it or press MAX. The reason is so that you windows don’t fog up. Even when you press max, the car will only recycle air for a limited time, I think 5 mins. However I have found that if you are in a very hot environment 90f+ then the windows will never fog with recyled air. You can also apply never fog to you windows.

lkchris

Here's the REST of what the manual says:

You'll note that "high" is not defined.

Note also that this apparently only occurs when a/c is turned on before starting car.

Nevertheless, air should be cool and pressing the button not required.

It's my experience that the ONLY advantage to switching the system away from AUTO is to enable manual control of fan speed. I remain unconvinced that temp setting has any effect except in AUTO mode.