J Tinsby

I am referring to the button on the console that says A/C OFF. I want fresh air from the outside not cooled air from the A/C unit. The button marked '0' shuts everything down as it should.

At times I can get this to work by pushing the button, and waiting for the residual cold air to leave the system. Other times I can drive 25 miles and I am still getting cold air even though I have the button AC off depressed and the red LED is illuminated.

The dealer is giving me some nonsense that the OFF doesn't really mean OFF ALL THE WAY..( sigh) they interpret this to mean this is an economy setting. I'm not buying that and the manual backs me up the compressor shouldn't run at all when that button is depressed. My Infiniti did have a setting that said ECONOMY but the SL500 surely does not.

I will also say that my wife's '04 SLK acts the same way, at times you can get just fresh air with no A/C air coming out of the vents but it doesn't work all the time.

Is there a certain setting for the other buttons on the SL500 to make the A/C OFF work like I want? If so I can't find that combination again.

Thanks to all who reply,

J T

ToonArmy

Yes, I've noticed the same thing. I seem to recall reading something that implied this was by design (Mercedes engineers are convinced they know better than you do what you really want).

I've usually found that switching to a/c off, then "all off", then back (toggle the "all off" button, which goes back to "a/c off" seems to do the trick.

GOODENUF

I had an 01 SLK320 that had manual A/C and heat. When you set the dial to the 6 o'clock position the system was off and the vents were closed. If you turned the dial to the left one notch - 7 o'clock position the vents would open but no compressor or fan would operate.
The A/C in our 01 E320 was just a pain. The sensors always overreacted the auto settings. The fan would blow low or high when it should not have.
The A/C system in our 07 SL550 works great but I have yet to figure out how to have vent only.

xtianpel

The STUPID things dealers say! My AC works exactly as you would expect.

Here's how you can prove to them that what they're saying is NOT true.

Do as previously mentioned, AC off, blower off then blower on. Make sure you're NOT getting cold air, preferrably on a hot day. Drive to the dealer and say "It's broken" the "economy" setting you mentioned is not working. Of course, you have to be smirking when you say this.

Then have them bring out the person that fixes A/C in their shop and speak to them directly.

Good luck.

SLR199

Perhaps that dealer explained it wrong. The compresser is a variable speed compressor. It is always running. Even when the 'OFF' button is pressed, the compressor still runs at a very low speed.

glennbaz

I've never heard of a variable speed compressor on a vehcile. Please inform me of how this works if you have any idea. Any compressor on a vehcile I know is subject to the speed of of the pully system ratio and RPM of the engine. The compressor is turned either on or off by the electromagnetic clutch. I have always been under the impression that the "AC off " simply prevents the engagement of the clutch there by reducing engine load.
Glenn

SLR199

From what I understand (I have been a tech. apprentice @ Benz for 7 months now), there is a plate on the inside in which 6 pistons push against, and the speed depends on how much or little the pistons move. It never completely turns off. I came from 3 years working in an indy shop servicing mainly domestics, so I had no idea what they were either. If you would like, I can ask my "master" about them and give you a more defined answer on Monday night.

glennbaz

Thanks for the input. As far as the "how far the pistons move" I wonder if it's a cam process that changes the "lift" depending on how far in the cam is inserted or something like that. The old Porsche mechanical fuel injection systems had something like that if I rememeber correctly.
Glenn