underdog01

(2007 s550) I believe my suspension air pump is going out as it seems to blow a fuse every couple of days, sometimes they don't last that long. But as a simple and less expensive resort I figured I would try replacing the relay first. Now I know I should have purchased a genuine OEM relay from mercedes, but my tight *** thought, "hmm a relay is just a relay go get one at your local friendly neighborhood NAPA autoparts store." I brought the relay I wanted to replace in with me and handed it to the guy behind the counter. He looked it over and double checked the part with his computer. Then he walked back into the bowels of the store and was gone for quite some time. Finally he emerges with new part in hand. It was a different color and even shaped a little different. But the prongs lined up correctly and that is all that matters right?! So I plug it into the correct slot and.... The starter begins to turn the motor over, only it doesn't fire because the fuel pump isn't running. At least that is my guess. But wait, that's not all! Smoke starts to roll out from behind the fuse box. Keep in mind this all took maybe a whole second before I was able to (quite panic like I may add) dislodge the relay from the fuse tray. After I and the car had a moment to settle down I tried started the car without a relay in place. Just hoping whatever just fried wasn't anything to disable the car completely. Fortunately, the car fired right up and I drove it the two blocks home. Once safely in my driveway, I installed the old relay and started the car again. Everything seemed fine. Then I systematically began flipping or pushing every switch and button in the car in an attempt to find what just took a crap behind my fuse box.

Found It!!! I no longer have control over the **** pit air temperature. I can control the fans, I can make the temperature number increase and decrease, but the air only blows cold. I can turn the A/C on and off, which is good, I had just fixed that on Tuesday. So, anyone have any idea specifically what I just fried? I hate electrical, and it is not my forte'. Plus the task just to get behind the fusebox looks like a major PITA. I had just decided to keep this car for another year too. I have been looking at a 2013 and couldn't justify it, it is looking more justifiable today.
Any help you guys can offer would be greatly appreciated. Thank you!

underdog01

*cockpit* air temperature. LOL

becosemsaida

Seems like you have to hook it up to DAS ........ It will tell you something, a "cheap" relay for the pump might just be an expensive repair after all......

So, there is a SAM behind the fuse box, you might have been lucky and it might be repairable. But my advice is to take the fuse box out (not so hard to do just be patient) and check what burned. Last option is take to a good electric auto shop and let them figure it out, if they identify what you need and you can always go shopping on ebay. You mentioned that you want to keep the car: see it as an investment.

To sort out your pump problems check for leaks, the fuse will blow if your pump is working full time, there is also the valve block that can be damaged and you are loosing air somewhere.

Beco