Blower motor stopped working. Applied 12v direct and it runs full blast. I read several forums and decided to replace the regulator. Blower still does not work. What do I do now? I live in Michigan and it is very cold! Please help!

Maybe the control unit, N22 is bad. . . not producing the reguired 'drive-voltage' as the blower wheel (my car has a 'potentiometer'; your car fan blower control) is advanced. If it's N22, that's rare in my experience.

__________________
Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

Everything is put back together right now. If I ground the motor to the frame, it runs full blast, so I know that it is getting power.

I'm an electrical goober. I can say that my '97 S320 had it's blower motor regulator replaced under warranty long before I bought it.

Steve

The speed regulation is in the ground leg, if you ground it you bypass the regulator. The control unit could be bad, the control units had a self diagnostic mode see sites
http://www.continentalimports.com/
or Jims site
http://pages.prodigy.net/jforgione/MB_S500.html

Forgot about that!!!! Peter, tnx for the reminder!

Use MENU#15 and check out #8 in the "operational checks". The reading should change as your select different blower speeds.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

I am at my wits end! I ran the test and it gives me a reading from 10 to 60 when I adjust the dial.
I am quite confused. Control unit seems to be functioning, replaced blower motor regulator.... Why won't the blower function?
Engine light is on. I ran other DTC tests and came up with the following list of problems:
E006 E073 E074 E075 E082 E083 E086 E087 E102 E103 E106 E107
Could any of these be contributing to my problem?

I assume you mean that you ground the blu wire and not the motor frame ??

If so, then you want to check the voltage at the yellow wire going to the regulator with key on and defrost position. That is full trigger for the regulator . With voltage there , the reg will complete the blu wire to ground , resulting in full fan.
If no voltage at yellow, Control panel is not sending the trigger to regulator.

Re-read post#8

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Post 8 tells you that the CP show trigger voltage at the CP..it does NOT tell you if there is voltage at the yellow wire at the regulator.

The test is to check right at the regulator for 12v from red to blk and trigger voltage from yellow to black.
If he is grounding the blower motors blu wire and that gives full fan, then either the reg. is bad, the reg does not have proper feed , or the reg is not grounded.
Having the CP detect voltage output at the CP does not insure one has voltage at the regulator. Specially considering that he has already changed the reg and grounded the neg side of the blower, getting full blower.
My guess is the reg is not grounded...........but I would do the voltage check at the reg plug first.

I am also having this problem on my 96' S320. I checked with my volt meter using my red lead on the blue wire and my black grounded on th frame. I got between 3 and 4 volts with the car running or off. I must be doin something wrong.

Parked my 97 S500 for 3 days at airport, AC was working.
When I started car the fan was not working. Prior to that the fan seemed to slow from time to time. Since it happened so suddenly I am thinking it is the regulator. How do I test fan?
Thanks

Gain access to the blower compartment

Look at the blower motor and you will see a red and blue wire connected to it. Jumper the BLUE wire to ground (Yes, it will spark!) If the blower is good it will start to run at full speed.

The regulator works by varying resistance to ground, so this test effectively bypasses the regulator. BTW, this test will work with the key on or off because the red wire is hot all the time..

Edit: Found the DIY with pictures: http://www.peachparts.com/Wikka/W140BlowerMotor

Regulators aren't too cheap, but they're an easy DIY to replace.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles