K-A

Anyone know what this could be. It's been occurring for a while now, but lately happens more frequently.

I'll have the A/C on, and all of a sudden, while the power is still on, no air at all is being blown out of the vents. I'll have to turn it off and on several times, which usually still won't work, then start playing with all the buttons, and eventually it'll work again.

loudbmw

My wife's '05 C320 did the same thing. First they replaced the fan control module - no change. Then the fan motor itself which seemed to work.

Lou

Diesel Benz

Do you mean they changed the fan control module that seemed to be working or do you mean the change fixed the issue?

On other models it is usually the regulator that fails. The symptoms can vary from the fan stopping intermittently to the fan blowing at full speed. Are you sure they replaced the motor and not the regulator or perhaps they changed both (the regulator is attached to the motor).

ralfvin

If you are experiencing reduced airflow and cooling after driving for a while, the cause may be the evaporator has become frozen. Under certain temperature, humidity and driving conditions evaporator temperature control may not be optimized since the deletion of the humidity sensor starting with 7/05 production. Mention DTB P-B-83.00/102 MAY07 and dealer will install a humidity sensor.
My dealer looked up the service advisory and installed the missing humidity sensor at no charge. Problem solved.

Barry45RPM

Its a bad blower fan control module located somewhere under the dash on the right side of the car. Mine had to be replaced twice to get a good one (on my '04). What triggers it usually is when the blower fan enters the highest fan speed aurtomatically, or you press Hi or Max or go into defrost mode. Its almost like the fan draws too much current & then trips off line untill it resets. All the lights & indicators say that the system is working except... no fan. Its random & an intolerable condition. It is a well known problem with a well known fix.

K-A

Yup, that's the one. Is it an extensive fix? I.e do they have to remove the dash or any of that stuff? Fortunately I have a Warranty.

Barry45RPM

No major dismantling... all from under the dash if you're worried about them "tearing apart" your car. It was returned to me as an undetectable repair... except that I never had the problem again after the 2nd replacement.

MB211

That is the only part of a repair that you SHOULD detect!!

K-A

Cool thanks. Yeah I was hoping they wouldn't have to tear the car apart or anything

The problem now is, getting them to "witness" it, as it's completely random in when it decides to act up.

konigstiger

Mention DTB P-B-83.25/76c, check your email.

K-A

Thank you!

KL2DC

Thank you. I've just experienced my first incident. I will continue to monitor my a/c performance but it did happen as you said (a/c switched to higher fan speed etc.)

Barry45RPM

As I said... well known problem with a well known fix. I wouldn't monitor anything... they know about it, plus there's a DTB. Make an appointment, get it fixed. You get stuck on a hot day on the road & you will not be a happy boy... and if you are unlucky enough to have someone else in the car with you, all you'll hear is that you "should have bought a Lexus". (Can't believe it happened on an '07 though).

doxland

Had this trouble with fan; would just cut out on full.
Dealer claimed a resistive element of the controller was replaced.
OK now.

kkanuck

Hi konigster,


Can you by chance tell me if this DTB P-B-83.25/76c would still work with the dealer on a 2006 E320 CDI? Is there a way to diagnose this for sure as the dealer is rather far from where I live? Meaning the humidity sensor.

I had the symptom arise for the first time this past weekend.

Hot day, long 9 hour drive, and after 6-7 hours or so into the drive, air ceases to blow in the normal velocity even though it sounds like the blower is turning. The A/C air is blowing like there is no fan turned on, so basically hardly any air coming out of the vents.

If I put it on defrost, still no air, or next to no air should I say.

I remember reading something a few years ago about some HVAC valve that is under the windshield driver side that fails if my memory serves me well. This is what is feels like, the fan blower motor seems to be making a noise, yet no air comes out almost like the duct is blocked, but once again, this is just my theory.


Any assistance would be greatly appreciated to lead me in the right way. I am good with electrical troubleshooting especially if I know what to look for.


Many Thanks in advance.

konigstiger

Your VIN is not included in DTB. Check both blower (current part # 2118300908) & blower regulator (current 2308216451).

http://workshop-manuals.com/mercedes...ns/page_15906/

https://www.google.com/url?sa=t&rct=...,d.cGU&cad=rja

kkanuck

Thank you for the links konigstiger,

The more I read, the more I know the evap tube must have frozen and that caused the problem. I drove 700 miles straight, it happened after 3/4 of the drive was done, weather hot humid, all during the day. I parked it for 90 minutes then drove it for 15 minutes before calling it a day, and it was back to acting normal, like the evap freezing had thawed. Once again, I did not get a visual, but it seems like this will be a rare occurrence if this long drive is a requirement to reproduce the symptom, time will tell.

I guess I should invest in both the motor and regulator as they are a known problem and its just a matter of time.

Christo Brits

I have found that when it happens to me (air fan blows harder, but less and less air come out the vents) then I switch off the AC and put fan speed to max for a few minutes. After that it works fine, which makes me think something freezes up somewhere...

vagt6

My 04 E320 has a similar problem. A/C fan works for a short while when outside temps are high and hot, then reduces fan speed to level 3 and won't go higher for some time. Not sure if related, but the cigar lighter in the console (2 of them) also goes dead when the A/C motor thing occurs (thus can't charge iPhone). Strangely, the A/C fan may (or may not) resume normally at any time, usually after a stop/start at a traffic light, etc.

Very strange, annoying and hot when temps around here in VA rise into the 90s.

Ideas?

Slider

My 04 E55 did this a few months ago in Arizona when temps were over 100.

I drove it around for a few minutes and thankfully it started working again.

Anyway, FCP sells the part for $117: https://www.fcpeuro.com/products/mer...tor-2308216451