tll29

I was out of town for a couple of months. Upon return and taking my GLK350 out for a drive, the vents aren't working. Whether I have the heater or air conditioner on, absolutely no air is blowing out. We checked the fuse, but it wasn't burnt out. Any suggestions? Thanks

GLKKa2H

Assuming you haven't had a trickle charger connected in the meantime, little charge/low voltage of the battery may be the culprit.

In the event of critical low voltage, some systems drawing heavy current surges are switched off and the power of the ventilation blower is also automatically reduced to 50%. Maybe even that one is switched off, given the voltage is really low?

Time to give the battery a good recharge from an external source, or go for a minimum of three - five hours drive

420tee

Good info, thanks.

wongmat5

My Wife's 2013 GLK350's cabin fan is having similar problems of not blowing air out. The temperature outside is about -20 celsius these days. Even after we warmed the vehicle up to about 80 degrees celsius, the cabin fan still won't trigger. The display shows the fan speed, however nothing is blowing out even if we switched it to max - very little air is pushed out at the vents. When we reach higher speeds on the highway, the fan works. I am not sure if the battery is not having enough charge, even though it has only been 2 years with 38k KM driven.
I wonder if the ECO start-stop function is draining the battery and causing the fan to not function - due to lack of charge or if there is something more critical happening. Any thoughts?

MBKLUE

If the battery voltage is good and the fuse is good I would think you could have bad brushes on the fan motor however, unlikely since they typically last a very long time. Somewhere there should be an SCR (silicon control rectifier) that varies the actual fan motor speed via control input from the fan speed adjustment buttons and other circuitry. That could definitely be a culprit especially if it's in a location subject to over-heating. That would be a poor design layout but it could be the case.

It's the electronic component that would carry the highest electrical load for this circuit which tends to increase the chance of it going bad versus other parts.

wongmat5

After going on the highway last night to charge up the battery a bit, the fan seems to work this morning. We will know later today if the deep freeze is affecting the battery output. I researched online and it seems that at -18 degrees Celsius, the battery output is only about 40% effective. Today is another -20, we will see how it turns out on the drive home after work. Hopefully it's just the battery that needs a boost or replacement and nothing critical like the SCR..

Will keep you posted after we get it checked out.

kerrly

I have had this problem before and it turns out that the fan motor was getting frozen. There is a known problem with the intake sucking in snow and moisture which ends up right in the fan motor.

Give this a try the next time this happens. Pop the hood and right up against firewall on the passenger side, there is a large black plastic housing. It is held on by three clips which pop off easily. If you can't see the fan motor start the car and make sure the fan is turned on the lowest power setting and so that it is not circulating the air. This will expose the fan motor. Grab a blow dryer and run the thing in there for a few minutes and see if that doesn't help it. If the motor starts, leave the blow dryer in there for another ten minutes to help evaporate any moisture. After doing this, it wouldn't hurt to let your vehicle run for another 15 - 20 minutes with the air circulating as that will run the warm air from your cabin through the fan motor and thus should evaporate any moisture from your fan motor that may still be left in there. Make sure the vehicle is warm though.

The only way around this is to make sure your intake vent behind the passenger side wiper is clear of snow before starting it in the winter. Ever since I have been doing that, the problem has subsided.

Rackasa

Hello,

As the title says, my airflow has all of a sudden been severely decreased for no apparent reason.

the blower works as I can hear it clearly at the different speeds. The AC works as I can feel the small flow of cold air.

My assumption is that a main air duck has been somehow disconnected. Air is being created but 95% of it is not making out of the vents.

Suggestions are appreciated.

thank you

Mmr1

When is the last time you changed the cabin air filter ? Mine reduced airflow after about 30000 miles noticeably .

Rackasa

not sure but I have been following the usual maintenance schedule with the dealership. The change in air flow was instant and happened while I was driving.

KanataSteve

Had a similar problem in -10, -20, -30 C. winter weather. Fan would start MOST times. Drive for a bit, shut off and miraculously it would start blowing again. Slow speeds sounded like something chattering. Waited until late spring and removed the fan motor - what a bugger to re install.

Found it was incredibly dirty with carbon motor brush dust, and found an exposed (non insulated) inductor (there are two) was about a hair's thickness away from the metal motor frame. It was covered in motor dust right over to the metal frame. Did it cause a high impedance path the the frame? Not sure, but possible. I have taken microscope pics underneath transistors with similar problems - get rid of the conductive dust with compressed air and no more electrical fault. Moved it over a few millimeters for clearance just to be sure, the other had much better separation.
Took the motor off the mounting plate, swished it outside in a plastic margarine tub really well in rubbing alcohol (about a litre), spun the shaft to get the guck off it, and shook it out and blew it out well.

Clean the fan as well - really improves air flow in *any* fan assembly.

Left it in the sun to evaporate the remaining alcohol and dry well. Shook it, found no droplets, so it was ready to reinstall on the mounting plate and reinstall under dash.

Reinstalled it and have had zero further problems.

To remove and clean, you have to remove the passenger side under dash cover plate, move the seat alllll the way back, disconnect the wiring, press on the little plastic locking latch and rotate the motor and mounting plate about a quarter turn, then it drops out.

Replace/clean the cabin air filter while you're in there.

Replacement is just the reverse, but I had to be on my back, pushing upward on it really hard and rotate it into position. I'm 6' 1" 190 lbs, so not really skinny and didn't fit in there very well to work, haha.

Took about 10 tries because it didn't seat level - one of the mounting tabs would invariably not go in place causing it to mount crookedly. Finally got it in place, reconnected it and it works like new. You should have seen all the solids that dropped to the bottom of the washing tub - incredible! Kept the alcohol for other cleaning projects, discarded the settled out guck.

Spoke to my very trusted ( ! ) dealer customer advisor about it at Star Motors in Ottawa (absolutely love them), and he laughed and said that they use the skinniest tech they have to do the reinstall.

It has been about 6 months now, all working great.

mogulman

I have a 2013 GLK with 145k. Fan started making noise at lower speeds a few years ago. At the beginning of the summer, it was making more noise at high speeds. I ended up ordering a new blower from FCPEuro for $138 here (price is more now): https://www.fcpeuro.com/products/mer...tor-2128200708

Took about 30 minutes to remove and install the new blower. Much better airflow now. Old blower did have some foam stuck in it (probably from a filter), but also it was much harder to turn than the newer blower. There are videos on youtube on how to replace it.

Definitely an easy fix that may be worthwhile, if you are having issues rather than making the old one limp along. The part above is a Mahl Behr motor (I believe same manufacturer of OEM). OEM original part is like $454.

roadtalontsi

Sounds like the cabin filter came loose. Likely installed incorrectly. If you still here the blower motor as you stated it is functioning. Take it by the dealership you get service from and have them reinstall it correctly. should only take a real tech about 2 minutes.

Rackasa

Thank you all for the suggestions / reponses. I did change my blower fan several months ago which was tricky but worth the effort. That out an end to the squeaky sound at slow speeds. I think I may have moved the airfilter by mistake in doing so. I will buy a new one and go back under the glove box for round two.