wilsemail

S500, 120K miles, No cold air. Climate control seems to be instructing okay. Blower motor fine at all speeds, ducting okay. EC light on, never off. No compressor engage. Check all the fuses I could find, they're all good. Pushed REST button, (as I read for another vehicle...) until "NR.OO +33.6 C" appeared in the A/C display. Now what???? Thanks.

schwarz

try pushing the EC button to turn it off.

if it is on then it means that the a/c wouldnt be blowing cold air.

Peter Guenther

The EC button shuts off the compressor, no compressor no AC. The system could be low on charge or a pressure sensor could be defective.
I had a similar situation, light would not go off no matter how many times i pushed the button, new sensor and recharge the answer.

wilsemail

Yes, it doesn't go off no matter what. I was told that it was charged. I put the gauge on the low side and it showed 45. That was a few days ago. Today it is about 40. Probably a leak somewhere. I can see dye all over the suction valve. Someone was probably looking for a leak. I added some more 134 just now because my other car, just sitting, is at about 65 on the suction end. ....Still no compressor. I'm on the way to test the pin readings of a new switch before I buy it. I figure the resistance readings on mine installed should be the same as one that's not attached. I'll keep us posted.

wilsemail

Well, it doesn't look like it's the temp or pressure sensor in the Receiver/dryer. I think someone told me at the dealership to reset the system. But I'm pretty sure it needs a Mercedes scanner to do that. I have a scanner but not a Mercedes one. And my software doesn't cover the AirConditioning system. Is it possible to reset the Air Conditioning system without one? This is a 2001 S500 by the way.

wilsemail

Here's the final outcome. I couldn't hear the compressor engaging because these new compressors don't click on like older compressors...they're always kinda on, but variable as needed. However, it still was not engaging, or whatever it does, because when there's a fault, the EC or ACon button stays lite no matter what you do. I bought a scanner that gets into the AC system. That's the only way. Got into the AC system computer and it said the system was low and that the evaporator temp sensor was bad. I cleaned the sensor and since the system was already recharged, just deleted the codes, and the EC switch started working again. Cold, Cold, Cold!!! I bought a Matco Determinator scanner with the 2005 European Starter Kit. I also had to buy a OBDII Smart Cable in order to access the systems. Man, if you don't have this or another scanner, you can forget about trying to find all but physically obvious problems. I paid $950 for the scanner on ebay. But only had the 2003 European software which was not good enough to get into the ac system. So I spent another $429 on the 2005 kit. Then I bought the 2006 Domestic an Asian Kit for $650, this kit included that famous OBDII Smart Cable that you absolutely need!! Now I'm a pro.

mugsy415

Sounds like ur a tech guy, but how much wouldve it cost 2 do what u just did at a shop?

fusion2007

my dealer said it was low on charge so they drained it any charged it back up... yeah...that didnt really help me soo much. it really did do anything.. u mite need fryon.. just so u know the a/c motors in the early 03's from 00 were terrible.i posted this in the other but yet similar thread

"iv noticed almost anybody who has the problem has an 00-03 and some early 03's have this problem.. mb changed the ac unit in the newer models because they recieved many complaints that the a/c fan motor was not strong enough.
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stevescoots

nice fix, mine has a simlar fault where abouts is the AC temp and pressure sensors located?

and I read you can reset the error on the dash controls

bankerbrent

Can someone help...........I have a 1999 SLK 230. I was driving down the road with the air blowing cold. My son pressed the EC button and the cold air turned to hot. Now I can't get it to blow cold anymore. Suggestions????????