Hello, everyone.
I just removed and installed a brand new blower motor for 95 E320 Wagon. The motor shaft on the new motor was bit longer than the original motor. No problems in fitting the squirrel cages, one on each end. Motor was ordered thru Autopartswarehouse (free shipping). Problem is that it still does not work! I checked fuses. It seems to be okay. Funny thing is even w/o the fan motor, A/C compressor and heater worked. It just did not blow air out. Could it be the switches or fan motor regulater? Any idea what I should do next?

If you have 12v at the red on motor , then ground the blu wore ..that will test the motor

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A Dalton

Thank you, Mr. Dalton for such a quick reply. I'll check it and find out if there is a power at the red on motor.

OK
If NO, then check the strip fuse up by the shock tower.
If yes, then ground the blu wire ..if that does nothing , then the motor is bad. If ground test works, then Reg. or trigger signal to reg. [ yellow] is bad

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A Dalton

Mr. Dalton,
I'll probably have to test tomorrow since I already spent 3:30 hrs this morning and I have to work to make money. Meanwhile someone suggested to check blower motor relay. I've been looking at Mitchell repair manual on CD, and I don't see that relay. Is it same as "Electric Blower Control (Rear of engine compartment)"? If so, what does it look like? And, yellow, is this one of wires for the blower motor regulator? I'm just curious, how could this regulator go wrong when there are no moving parts? It looks like a few wires are soldered on to the aluminum plate. The only thing I can think is that the wire must be cut somewhere along the way or came apart at soldered point.

Your car has no relay..
The regulator is a Switching Transistor/voltage regulated circuit , so of course it has no moving parts ..they burn up or short inside.

The yellow wire is trigger voltage from the Control Panel to trigger the switching transistor on the ground side of the blower circuit..so, if you just ground the blu wire like I asked, you will see that that ELIMINATES the regulator out of the blower circuit for a DIAGNOSTIC TEST. That is what the reg does ..it GROUNDS the neg side of the blower motor..it is a SWITCHED GROUND circuit.
SOOOOO, this is what we do ....I give you the sequenced test procedures and you do them and report the findings..I then tell you the next test and we will finally get to the solution/remedy.

The first test was.... do you have 12v at the red wire at the blower ...so, when you have time , that is where the diagnosis starts and then go to the second test I posted for you [ ground the blu wire] ...

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A Dalton

Mr. Dalton,
Yes, sir. I'll report you as soon as I get to it, sir.
Thank you for your reply!

Sir ????? .....I am here to to aid you , nothing more..

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A Dalton

Mr. Dalton,
Good Morning!
Yesterday, I spent all day to figure out why brand new motor has not been working. Initially I had a problem that I was not getting power at the red wire. I've Mickey Moused for a while and I found out that 15A fuse at Auxillary Fan relay was blown. It took me good 2 hrs to figure out. As I replaced the blown fuse, I got power at red. So, I grounded the blue and yes, indeed the motor ran. Then, I re-connected the blue. Reading at red and blue was 12v and the motor was not running. So, I came to a conclusion that I have a bad fan motor regulator. So, instead of putting everything back together, I removed the regulator. This task was a pain in the rear due to the "V" groove. I was not able to just slide the regulator out! I had to disconnect the wires at the plate and as I was pushing down the plastic mesh (I think I broke couple of the mesh), then, I was able to slide out the aluminum plate. Why is this thing so expensive? I think the fan motor is a lot more complicated and uses much more copper than the regulator. Do you have any recommendation where I can get a good quality regulator w/ better price (cheaper)?

You are going way off track..
The Aux fan relay and 15A fuse have nothing to do with the Blower motor ..they control the aux fan in front of the radiator. And if you were not getting power to the red at blower until you started fooling around up at the aux fan relay, I think you may have a hairline crack fuse problem at the fuse-link over at the left shock tower..that needs to be checked first as it is a common problem and may even have been you trouble from the start..check that w/test lamp. on both sides of the fuse holder. That is 12 V feed to red at motor [ test #1]. If that is the problem , you may have not even needed the motor..................
And you do not have to take the blue wire off the reg or motor ..you just place a juimper wire on the blu terminal at the motor [ step #2] and ground the other end after you have confirmed 12V at RED [ step 1] If that gets you blower full speed , then you have to see if the yellow wire at the regulator is getting variable voltage ..that is what triggers the regulator...NO V at yellow wire equals No fan b/c the reg is not seeing a trigger from the control panel. That is the regulator test and is the 3rd test , the first being RED V at motor and Jumper from blu to ground to test motor as test #2 ..you have done those and confirmed blower and power to blower , but you have not tested the reg yet....
If you would like to assume the regulator is Bad and want to change it , fine...but the correct way is to see if the reg is getting a trigger signal from the Control Panel...if it is , you are correct in replaceing the reg,... if it is not , you have just wasted some big $$$$ 'cause the new reg is not going to work any better than the old one w/o a signal at the yellow wire.....
This test sequence that I am giving you is a standard 3 part test for blower and it is all done at the 3 connector plug behind the brake booster...That allows one to check for power to RED , ground at Blk, and regulator trigger at yellow without taking ANYTHING apart..you just open the hood and do the test right at the plug.
You then know if you need to go down into the motor compartment .
The CP, fuse link, blower power feed , and reg trigger sigs can all be tested right there on top before taking anything apart.

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A Dalton

Mr. Dalton,
I did not mention in the 1st email, that I checked power on Yellow at the regulator. There was no power. That's why I removed the regulator. And, I thought Auxillary Fan was for the fans in front of the radiator. Since the fuse was blown, I just replaced it. I had replaced the fuse (not OEM) and I frequently checked power at both sides of this fuse. If there was a break in the fuse, I still should be able to detect power coming in, shouldn't I? But, there was a time that there was no power at both sides of the fuse. Funny thing is that when I replaced the fuse for the auxillary fan, I got power at both sides of the fuse. Mr. Dalton, what is the chance of having the bad push button switches? How do I check if I have a good/bad push button switches?

If there is no power coming into strip fuse , then the suspect is the Ign switch. Put a Test lamp on the fuse in-line and jiggle the ign sw a few times .

Aux fan still has nothing to do with Blower circuit, so forget about that..you just happened to have a blown 15 A fuse for low AUX fan b/c that fuse has been upgraded to a 25A by Benz and they all blow w/15A... aux fan is a completely different system..you have just been driving around with no aux low fan for a/c operation w/o knowing it.... That's all. That fan relay is triggered by a pressure sw that keeps the a/c systems high-side pressure inside the condenser in check by adding aux air across the condenser. That is ALL it does and is ALL it is there for. And it NEVER comes on w/o a/c being on.
SO,....Another simple test w/o getting to blower and regulator is to bring a jumper wire over to the strip fuse from the battery Pos + terminal..that eliminates the possibility of bad ign sw. Then try blower on Defrost CP position.
If you have no power at yellow , then suspect is Ign sw or CP.


Give those findings ..

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A Dalton

Mr. Dalton,
I'm okay for now as far as power is concerned. I'm getting power at both sides of the non-OEM fuse. If it happens again (no power at both sides of the non-OEM fuse), then I'll test the ignition sw. And, I've already removed the regulator and I also took it apart at the aluminum plate connector plug. So, it's been RIP. I'm trying to find a new/used regulator w/ best deal possible.

OK..

Just remember , if you have no variable voltage [ 2-9v. depending on fan speed selection], the regulator will not ground the neg side of the blower
[ blu wire side]. That is what the reg does..it is a switched ground circuit and that is all controlled by the yellow wire V signal. The red side of blower is ALLWAYS hot w/ign ON , so you can now see why we ground the blu wire to test the blower if we know we have 12v at RED . Grounding the blu wire simply by-passes the regulators switching function and allows direct Battery 12 V to blower .....Simple as that.
Many guys with old chassis that don't want to go the $$$ for a reg. simply put a toggle sw in-line with the blu wire to ground and settle for high fan only , with the toggle mounted under the dash somewhere for ON/OFF.
As I stated before , the yellow wire sig V can be checked right at the 3 wire connector at the firewall behind the brake booster. You should have 12 V at red to blk and 2-9 V at yl to blk with CP ON. If no yellow sig there , your new reg is not going to solve your problem b/c the reg will not trigger/switch blu wire to ground source to complete the blower circuit.

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A Dalton

Mr. Dalton,
I just want to express my appreciation for all the emails you've provided. My sincere hope is that the regulator was the problem caused the blower not to work. Looks like new regulator will cost $$$. Hoping I can find a good used regulator at a fraction of new regulator. Again, I thank you for your emails and I certainly notify you if I resolved the problem by replacing it w/ new or used regulator. Wish me a luck!