Hello Guys,
The light on the AC Off button is always on, which means the AC is always off. Pressing won't do any good, any idea what might cause this?

 

You & I both have these counterintuitive AC buttons - later changed to press for aircon ON.

Check you have not blown fuses 41 or 51

Perform a reset

Press and hold the "Defrost" and "Recirc" buttons together, and release only when the lights on both buttons start to flash back and forth between them. This procedure starts a system self-diagnosis of all components, sensors, etc., and then resets all the settings to the appropriate normals/default. The test runs for about 15-20 seconds, then the lights stop flashing and all returns to normal.

If none of this works you could have an activation solenoid on the blink or compressor problems. Have you extracted codes with an OBDII scanner?

 

I've checked the fuses and did the reset, nothing helped.
Didn't extract the codes yet.
Does this mean its a serious problem?

 

It's hard to say - It might be as simple as a switch failure - If you put the system on auto or windscreen defrost does the aircon still not engage? There is no clutch on these aircon compressors - they run all the time with an actuator that makes them pump.

 

By the way, there's a leak some where, forgot to mention that. I went today to have it filled, the guy told me that this light thing should be fixed first.
So putting the system on auto or windscreen won't help right now.
Does the leak might have something to do with it?
The aircondition stopped cooling a while a go, but I postponed the fix till begining of summer, since anyway I wouldn't be using it during the winter.

 

Huh! - you just answered your own question - your aircon guy obviously does not know Benzes

Straight translation from the manual. Sorry not perfect German to English

"As there is now no gas pressure in the system ,the safety/pressure switch will not allow the a/c circuit to function"

Get the leak fixed & the system regassed - Then it will work - darn smart cars these.

Good Luck Sorry I should not have assumed you had gas in the system.

 

Great, thanks a million
Will do that first thing tomorrow morning

 

I hate the counter-intuitive button.

 

Ok, I regassed the system, and the light turned off.
I still need to fix the leak. The guys couldn't pinpoint the leak, so they added a UV material to the gas and asked me to drive it for a week and then get back to them.

 

Excellent news! - hope they find that darn leak

 

well, Glyn,
I'm glad to see your wisdom here. I'm guessing original poster is talking about the EC Rest button light, as mine has been on the last couple of days. I had forgotten which two buttons to press for the self diagnosis, so I'll give that a try, but given the fuse issues I had (this thread), including 41, that's also a good place to start.

 

Glyn,
I finally had the time today (a hot one) to check that fuse #41 and it's fine!!?! Checking the fuse function list (which you've conveniently attached above), I note that air conditioner also lists #51, so I checked that and it's okay too. Don't know if it's at all relevant, but many of the numbered fuse locations on the list don't have fuses in them in my car, and in fact don't look like they'd take a fuse. 23, 24, 25, 29, 34, 35, 36, 37, and 41 look like they won't take a fuse, and 27, 28, 38, and 39 (plus 5, 6, 7, 11, 12, 13, 14, and 16 in the back) just don't have fuses in them.

 

Yes - I've posted the diagram for a fully loaded car - with all options fitted - If your car does not have the options there will be no fuse. I do this because I have no idea how peoples cars are configured & they give limited information.

Are you sure that your car is fully gassed? Have you done a system reset?

 

Is it defrost + recirc? I've done that with no results.

 

https://mbworld.org/forums/c-class-w...ghlight=Easter

 

So I had the same thing happen today in my 2003 Cl600 the A.C. Off button was constantly on as I was sitting in my car outside work for awhile, I started to get hot and the button wouldn't come off, ran the self check by holding the arrow button and Rest button- it did it's thing and now it's blowing cold again, pheww thanks!

 

Hi Andrew, I have the same problem as you in my 2006 CL500. Which "arrow" button did you hold along with the "rest" button? I'd like to try to fix my problem...

Thank you,
Tony

 

Tony read the entire thread. It tells you which buttons and what to do. Its the 2nd post. Come on dude

 

PEOPLE READ THIS:
This works aswell with an E320 and it solves the EC light problem.

My EC light didn't turn off. I tried many online suggestions about how to reset the codes and such. My E320 just didn't respond to those instructions, it didn't reset the codes or solve the issue. Finally I tried this person's method even if his car is another model (CL600), but by using his method (recirculating button + REST button, and turning off and on the car) my problem disappeared.

Link to my reddit:
https:/www.reddit.com/r/MechanicAdvice/comments/1krjjkb/ac_advice_on_my_2000_e320_mercedes/

 

👍 BTW- "EC" stands for Economy which is to say, you may get better mileage with the
AC off. So yes, pushing the Economy button turn off the AC not on.