A/C blower motor not working
 

Vehicle: '86 300E 124.030

A/c and blower were working well. Suddenly, the blower went dead.

I don't get any voltage at the red wire on the blower motor connector that is behind the brake booster on the firewall nor in the fusebox (fuse #12). Checked the fuse and it is good.

A few months back, I had the ignition switch replaced. I am thinking that something in the new unit is loose since I am not getting any voltage at either the connector or fuse.

Any ideas are appreciated.

Check the wires under the fuse holder..they burn off..
Also, on that year, there was an aux fuse holder modification that wires a 30A fuse/holder outside the fuse box, eliminating the 25 fuse/holder and upping to a 30A.

When you say "Check the wires under the fuse holder..", do I have to remove the fuse box for that.

Thanks.

Yes....but I would look around for an Aux fuse holder first...not many still have or use the original #12 fuse....
If you want to be sure and also check if it's the Ignition sw. [ b/c you mentioned that], just bring a jumper wire from the battery Pos + over to the #12 fuse and then retry the fan.. That will eliminate the IGN. sw feed possible.

Looking at your chassis schematic , the exterior Aux fuse modification was Factory after VIN end # A292112, year 1986.. Then they went with Aux Fan feed fuse F15/AUX Holder set up. 30Amp. Look over by the shock tower..Should be a link type fuse. That feeds the RED at the plug behind the Booster............

Thanks Arthur. I tested the aux. link style fuse that is outside the fuse box and it is good. I checked for continuity and it is good but not juice to the fuse - checked using a multimeter - red to fuse and black to body (ground) and I get zero reading.

Thanks. Will report what happens with I jump fuse 12.

<<Thanks. Will report what happens with I jump fuse 12.>>

NO....If you car has the Aux fuse update , then you do not jumper to fuse 12..you jumper to Aux fuse link.

Got it.

Jumped the aux fuse link and the blower came to life. I will either replace the ignition switch or fix a loose wire, which ever is the case.

Thanks Arthur for the info.

Before replacing the ignition switch see if slight back pressure on the key once it's started causes the blower to come on. It appears to be a fairly common problem with Mercedes ignition switches that there is some wear inside them causing the problem. My brother's 123 200 had that problem. He did not have the money to replace the ignition switch but was able to get the blower to come on with very slight reverse pressre on the key.

- Peter.

i have the switch problem, too..just back the key off

another friend has the same problem.

it's not the switch...it's the piece in back of the switch..i forget the name..

i replaced the tumbler switch on my 260e, that's how i know...

Many guys don't want the hassle of switch repalacement, so they just put a toggle switch in it's place ....

arthur...are you the anti Robert Goodwin... ? he is the guy over at mbca..that has a standard answer... buy the cd.

you, sir , have good insight and alternatives....

I come from the dear school of survival and yester-year solutions..the pre-duct tape era...When the tractor stopped running , we jerry rigged it 'til the cows came home....

I used to have that problem where I had to back the key offf a bit and so I replaced the switch - basically the rear part with the electrical contacts - in January and now this problem.

I am going to replace the part again.

you are right... i bought that rear part..but it seemed llike it would be a pain to replace...so i just back off with the key a bit.

i did have to do the switch... was lucky, i could get the key in the 2 position