cam69ss

126 HVAC Fan not working / Heater Fan Removal

Hello,

I have a '90 300SE and the heater fan stopped working. Before it stopped I did notice a very faint squeal when it was on. Anyone have a procedure on how to get to the fan and remove it? I understand you have to take the dash apart to get to it. I have a PS airbag so I don't know if that make it harder to get to. Is the possible to test the fan without getting to it? Any information or links would be helpful.

Thanks in advance,
Cold Dan in Worc. MA

'90 300SE 242K untouched eng/trans

braverichard

First of all, I hope you are aware of the fact that the automatic climate control on these cars are their biggest archilles heel -- or maybe I should say their second biggest, after vacuum systems. So be prepared if your troubleshooting ends up getting more complex than it currently seems.

Firstly, the blower motor is located under the dash in the front passenger's side. It is right under, you don't have to disassemble the dash to get to it. Just go right underneath, take off the plastic panel, then take off everything else in layers till you get to it. It shouldn't be a very difficult task and shouldn't interfere with your passenger side airbag at all. For me, performing the task on my Euro 500SEL was difficult because I am a huge 6'3" guy and I couldn't quite get enough space to comfortably get under there. This task involves standing on your head for a long time by the way!!

To answer your question: no, you can't test it without taking it out. That said, judging by the fact that you said it was making a faint squeel before it died, I'm guessing that it is really the blower motor that's dead and nothing else. For your own sake, I hope my guess will end up being the case. The first thing you should do once you take it out is to wire it up via your battery. The fan should blow on full blast if it works. If it doesn't blow then it doesn't work. Also, use a voltmeter to check and make sure it is receiving current at the power connection under the dash. At this point once you have everything verified (that the motor is dead and that there is current at its power terminals), purchase a blower motor (I have a used but fully functional one I can sell to you if you want) and then perform the replacement. Everything should be back to normal.

Let me know if you have more questions.

cam69ss

braverichard
Thanks for you help. I will check this weekend and if it is the motor I would be interested in it.
THanks and I will let you know
Dan

farooq

for comfortable working under ur car dash. especially if i happen to be a big guy.. a good idea is to remove the passengive side seat. spray some wd40..lossen up those bolts and there u go.. standing on ur head for long time can be dangerous and can cause excessive exhaustion or headache.. or even blood acculumation in the brain..

braverichard

Good suggestions there! However, the way I did mine was, I'd work in 15 minute intervals as that was an unnatural position. Didn't feel like taking the passenger's seat and seat belt off. And actually, most of the time you won't actually be standing on it, but it seems like a long time because it is such an unnatural position.

cam69ss

Hi again, before I try to get to the fan I was told to check the fuse. I was told there is a sep. fuse next to the fuse box for the fan. I could not find it.
I see a large resistor mounted next to the sway bar mount under the power brake booster but I think that is for the Aux cooling fan.

If anyone knows where this fuse is please let me know.
Thanks
Dan

cam69ss

braverichard
sent you an email about the motor.
THanks
Dan

braverichard

Dan,

Oh yes you should check the fuse before troubleshooting any electrical issues. Preferrably, replace the fuse with a brand new one and see if things improve or not.

The fuse for the circuit of the blower motor is fuse no. 11 in the fuse box. Should be a blue fuse. If you have a set of new fuses, go ahead and replace it and then try turning your air on to see if the blower then works. If you don't have a spare fuse, just take another blue fuse from your fuse box for a feature you know currently works and then use it to temporarily replace the blower motor fuse to see if it then works. Since I'm unable to take a picture of my fuse box right now (cold outside), check out this post I made sometime ago ( https://mbworld.org/forums/showpost....04&postcount=2 ). You can locate the blower motor's fuse in the picture of the W126 fuse box as follows: go to the row of fuses east of the row containing the labeled "fuse d", then go north to the fourth fuse and that's the blower motor's fuse. Also read the entire post to see what wonders a fuse replacement can bring about.

cam69ss

Thanks for everyone's help.
It was a the blower motor. Pretty close to being seized. Getting to is was not too bad and I am not a small guy.
I found a new bosch motor on ebay for $91 shipped to my house.
To get the fan off the motor shaft I sprayed it with WD-40 and let it sit overnight. THen I braced the fan in a vice and using a metal rod and a hammer it gave the shaft a couple of hard hits and the motor fell off.
THanks
Dan

braverichard

Congratulations!