Ticking noise from a/c blower fan

[suginami]

I have a 93 W124, M104 engine. I did a search on a/c blower fans, and most of the indications of a blower fan going out are a chirping or screeching noise.

My noise is a faint ticking sound, coming from the center vents, that goes up and down with the speed of the fan. It's much like the kind of sound when you were a kid and you put a card in the spokes of your bicycle spokes.

It's not loud, but is very annoying when the radio is off or the volume is low, and your not driving very fast. If I'm on the freeway and the radio is on, it muffles the ticking noise.

It's driving me crazy. I suppose some debris could have fallen in there, or something is going out that needs to be replaced.

How do I get in there to look around?

What could be going out?

thanks.

[suginami]

I think your situation is better than mine. My noise happens at all fan speeds...

[suginami]

I think I just might "marinade" on this decision for a while.

If there is debris in there, I'll give it about a week or so to work its way out.

If not, then I think I'll try and figure out how to get in there and examine if there is something stuck in there hitting the fan.

If no debris is present, Does anyone know if there is something to lube? If not, I'll consider replacing the whole assembly.

Did I read correctly when you said that the wiper assembly needs to come off to examine the fan?

Seems like an awfully strange place to start, but it wouldn't suprise me, you know, MB German engineering and all...

[euro 287]

Do yourselves a favor and dont try lubing the unit , replace it. They take 2 hours to install and dont get the cheap aftermarket retrofit unit. Get a good unit and if possible have it replaced by a professional so you dont break your windshield taking the wiper assy out.

[suginami]

So you think my ticking noise is indicative of the blower motor going out?

[Billybob]

Is taking the wiper assembly out on this model particularly difficult or unusual? If so why or how so? I just removed mine on my 126 and it was pretty simple and straight forward.

As to the ticking sound my fan had ingested a stray couple of pine needles that where at the root of the problem. I ended up removing the fan/motor and a quick cleaning did the trick. getting to it from under the dash wasn't exactly easy but certainly doable in a couple of hours. Don't know about this model but I think the earlier 123 cars where accessed from the wiper assembly bay area. Good luck!

Yeah I've checked out that site what he's got there is pretty informative and well done. But that goes to my point, it seems much easier to get at this blower motor from the outside than from the under dash area like in my 126. Breaking the windshield doesn't seem like much of a risk! Maybe if you drop a ratchet or wrench or something, maybe if your banging you head on it a little as you maneuver those metal clips! Seriously paying a tech for two and a half hours, I'd try it myself and reap the benefits of the lessons to be learn and save a couple of hundred bucks! Having someone else do the job ends up being a $400+ to fix after labor and MB parts to fix an annoyance!

[mplafleur]

I also have the quiet ticking in my 190E. It is only heard on the lowest speed setting. I replaced this fan 2 years ago with an OEM replacement. What is it with these fans? I've replaced them on every MB I've owned. At least I didn't have to remove the whole DA**** dashboard this last time.

[suginami]

I really don't think my problem is the blower motor.

The sound is real close to the center dash vents. The sound doesn't come from anywhere else.

When the air comes out of the two side dash vents, there is not ticking noise.

When the air comes out of the floor or the vents near the windshield, there is not ticking noise.

If it was the blower motor, the sound should be there regardless of where the air was coming from.

Does anyone know how I can examine the area behind the front center dash vents. The ticking noise is definitely localized here.

Are there separate fans that blow air through these vents only?

thanks.

[bluerhino]

Were you able to solve the ticking noise on the blower fan? I am beginning to have the same problem....

[jwiggin]

Here's a theory in response to Suginami's post. The vacuum pod for the defroster flap is mounted on the right side of the blower box, just behind the glovebox (at least on my 89 300E). I had a similar sound that "sort of" sounded close to the center vents but more on the right. Eventually it stopped. I took apart the vacuum pod, which is dual port and has two rubber diaphragms. One of the rubbers was totally trashed. That pod actuates when either the A/C button or the economy button is pushed to direct airflow to the center vents. Could be I was hearing the diaphragm slowly faily and flapping around from the vacuum.

[suginami]

No, the ticking noise hasn't gone away.

It comes and goes. Sometimes it's really bad, and other times it's so faint, that the sound of the car running muffles the sound.

I believe the blower motor is wearing out, and the blower motor fan blades are wobbling, and rubbing on something, causing a ticking noise.

The ticking noise is there regardless of whether I'm using the a/c or defrost, heat or cold.

[bluerhino]

Hi Suginami,

Any developments on the subject?

In my case the chirping noise starts about 10minutes after I turned the fan on. It is annoying that I have to turn it off and suffer a/c, blower less day during hot days.

Could this a be a blower fan blues? or is there a way we can lubricate them?

[suginami]

From what I've come to understand, you do have the blower motor blues.

I'm still monitoring the ticking. It comes and goes. Sometimes it's gone completely, sometimes it's very minor, and very occasionally, it's really loud. I know it is wearing out, and I'm just waiting for it to become intolerable. Fwiw, if you're cruising on the highway, and have your radio up loud enough, it drowns out all but the worst ticking.

It seems the blower motors just wear out and need to be replaced. I have never heard of any other car make in my life that needs to go through blower motor replacements, like our wonderfully, German engineered blower motors do.

I bookmarked a website that was called "the poor mans Mercedes newsletter", that showed a guy pulling his blower motor out and replacing the brushes. The site doesn't work anymore.

I don't know if this is a good or even worthwhile project, as there may be things other than brushes that wear out.

Fwiw, the blower motor is under the windshield wiper assembly annd motor, and apears to be a job that's not too difficult, and may take 2-3 hours.

I've experimented a little with disassembly of the wiper unit to look at the blower motor, and it seems like a DIY'er could do it.

To take out the wiper motor, you first open the wiper arm cover, loosen the hexagon socket screw, and remove the wiper arm. You then unscrew the 4 hexagon nuts, take off the retaining clip, unplug the electrical connection, then take out the wiper system unit. Then, you'd unscrew the hexagon nut of the wiper motor shaft, take off the crank arm with the attached linkage, and then unscrew the wiper motor.

Once the wiper motor is out, you can see the cover for the blower motor. The cover appears to be held in by clips. You can also see the outside air temperature sensor that you'd have to unplug.

Once the cover is off, I don't know how the blower motor comes out. I know it must plug in somehow, I don't know if it simply plugs in or needs to be rewired. I'm guessing the motor justs rests in there somehow, and can be pulled out.

Maybe Gilly or Stevebfl, or someone whose done this can help us out...

[suginami]

Well, it's been about 1 1/2 months since my last post, and the ticking noice has completely disappeared.

I am beginning to wonder if there actually was some debris that got in there.