jlw000

I have an E500, 2005, 27K miles. Today i went 1 mile to lunch and on the way the air, which was on automatic, suddenly shut off...though the read out showed it was on. I hit the on/off switch and fan switch and it shows the fan speed, but still dead. I thought, o.k. maybe a fuse. I parked, went to my lunch meeting and came out expecting it to still be dead. But to my dismay, the AC worked immediately (I'd been happy knowing it was a fuse). So now I am going to have to go to the dealer and have it looked at I guess. Any experience out there that would point to a specific issue? Until today I have had no issue with AC. thanks

Diesel Benz

Sounds like the fan regulator although I thought that issue was a lot more rare on a W211 compared to older models.

Barry45RPM

I had the problem on my '04. Whenever the fans whent into Max Cool or highest speed due to demands for extra cooling, the fans would shut off, but would work as you say when restarting a little while later. It was a fan blower regulator located somewhere under the passenger side dash that was faulty. Back then, they had to replace it a couple of times. I believe the part has been updated, and after its replaced, you will have no more problems like that.

jlw000

Well this is exactly the same issue i had in my 530i and am not surprised to hear this. In that car the part is roughly in the same place and was about $100. After it was replaced it was fine. I suspected the same thing here but as this is my first MB was not sure the engineering was that similiar. thanks.

Diesel Benz

I've had one replaced from a 5-series BMW, and one from an E-class MB (W210 though). I guess we can blame BMW.

ehr1

More than likely needs a a/c blower regulator. I replace 5 or so a month at work.

Diesel Benz

Is that for W211 models? How would you estimate the likelihood of this failure between different MB models?

deshelto

I have the same problem, just haven't had time to take it in yet. Good to see the posts about what the problem could be. As a short term fix, whenever I see the a/c jump in to "Max Cool" mode, I manually adjust the blower speed down one notch. For some reason, that is enough to make it not shut off. Then when it cools down in the car I just hit the "Auto" button again. Let us know what happens when you take it in for repair!

Barry45RPM

My uneducated guess is that in Max or Defrost mode the fan motor is drawing max current which the regulatior can't handle. Interesting that in the '07's the A/C must be manually put into "Max" mode by pressing a button, while on earlier cars it happens due to cooling demands made by the thermostat.

starbrite

Per previous post by Konigstiger (resident genius) :

" A/C Blower not running :
P-B-83.25/76b Mar 07- Blower motor stops running.

May be caused by high blower output requested by the climate syatem and the blower regulator overload protection engaging unnecessarily.

The blower regulator will be replaced wit part # A230-821-64-51 (updated #, 1//08) if need be ".

Happenned to my car and regulator replacement solved the problem.

TPAbnz

Same issue here . . . regulator replaced.

mcleantmw

The Display on the dash for my AC Unit controls is so dim in the daylight that I can hardly read it........at night it's bright enough to read. I tried using the little knob on the overall Display to adjust the brightness and it doesn't make it bright enough to read. The brightness for the Radio display is o.k. Does anyone know what's wrong........is it the "light" unit the AC Display failing and can just the Display unit be replaced or does the entire AC control unit need replacing?

konigstiger

Check your email

mcleantmw

Thanks for sending me the Service Campaign Bulletin but I don't think it applies to my situation. Even in regular daylight, not direct sun, the brightness on my Climate Control Display is so dim it's unreadable.......it's only readable at night. I researched on the MB Parts Catalog that there's a sensor unit under the hood near the windshield that operates the light dimmer and automatic rain detecting wiper blades. My suspicion is that this sensor unit is defective and is "locked" to be continually in the "night" mode. Why? Because when I tried my wiper blades today in the first setting, the rain sensing setting, they continually operated even when there was no rain. Does my diagonsis seem ontrack? The only other possiblity I can think of is that the Climate Control Display Unit itself is failing.

konigstiger

Sent the DTB to give a better understanding as to what might cause difficulty in reading the LED display. Were the display and wipers malfunctioning before you had it in for service, could have had it checked then and circumvented a trip back to the dealer.

mcleantmw

No, they just started acting up after my recent service. I have to go back in a couple weeks for another visit to my MB Dealer once the Transmission ECU they ordered from Germany comes in. So, I'll have them check out the AC Display and Wipers auto sensing at that time.

peterjthomps

I experienced the same issue with my Temp controls. It was related to the sensor located near rear view mirror. I had a new windshield put in and the sensor was not completetly connected. I would check to make sure it is completely secure. All I did was disconnect and reconnect everything and since then no issues. There are other references in this forum related to this problen, and one that has instruction on removing the sensor control near the mirror.

mcleantmw

Thanks for this input.......glad you mentioned about the sensor being located at the top of the inside of the windshield. I'll look at it in the morning to see if the electrical connectors are firmly inserted or not. The rain sensing wipers definitely do not work properly since they just keep operating in an intermitent mode in dry weather and the Temp Control display just stays in the night mode and unreadable during the day. Glad to know my theory about this sensor being the issue was ontrack!

jlw000

Where is that little "knob"? I cannot seem to find one that does what you describe.

BTW. I did finally get this AC problem fixed this week. They replaced both the regulator and the blower...under warranty.

Barry45RPM

The knob is lower left at the cluster. The same knob you press in to reset your trip info and other things. You can press it in and also rotate it clockwise/counterclockwise.

jlw000

i thought that had to be it and it tried it and did not see any difference, but now that it is confirmed, I will pay closer attention. thx.