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  #1  
Old 12-04-2010, 11:36 AM
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Location: Hillsboro, OH
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Exclamation Blower fuse problem W201 1984 190D 2.2

Good AM Dudes and Dudettes,

I have read numerous posts about the #1 fuse problem and the MB fix w/ the outboard 30A fuse. However, has any reader themselves actually put that mod (or a NAPA equivalent) in a 190D by accessing the bottom of the fuse block? It isn't reasonably possible ! However, one can get at the wiring from underneath the panel on the driver's side. BUT the under-dash wire color codes do not match (exactly) the service manual's colors nor can one tell exactly which fuse they attach to. Has anyone bypassed fuse #1 w/ a 30A new (ATA ?) pigtailed replacement. (BTW, yes, I have replaced the blower motor w/ a new one, it draws the same current the old one did - it just doesn't squeak now.)

Or is there a secret method of loosening the fuse block with its old, cold, stiff vinyl wiring and impossible to access crannies? Certainly there are NO hints in the MB manual, all their verbiage suggests the fuse block is out in the middle of a 40 acre field. Are there some other markings I am missing on the underside of the fuse block that would help identify the correct lead?

Any experiences would be greatly appreciated.

Doc Bill


I GOT IT DONE !

Here is some additional info added a couple of days after the above post:

Yes, the wiring CAN be accessed from under the fuse block by removing the under dash kick panel. A (NAPA, etc) pigtailed replacement 30A fuse with the spade terminals (I think it is called an "ATA" type fuse) can be attached w/ one each yellow 10-12ga wire "splices". The supply end is a 2.5 (~12ga) black/green/white and the lead to the climate control (and blower) is a red/yellow 2.5 (or ~12ga).

The proper leads to attach to are not easy to identify however I used a telephone wire tracing device and put a 'signal' on each side of the #1 fuse block and picked the wire with the "hot" signal. It DID match the color codes given in the MB manual. The wires are not close to each other, but in separate wire 'bundles'. This is a little high tech for the usual week end DIY MB work but it CAN be done. You could do the same thing with a continuity checker and some insulation piercing probe tips.

There are a couple other wires under the fuse block with similar color markings, but they are smaller diameter. The nice thing about these press on splices, you can test and remove with little insulation damage if you pick the wrong wire.

A small ice pick like tool I made with a little hook on the end makes it much easier to pull out and isolate the wire of interest during this job. Yes, the fuse is hidden under the kick panel, but if the blower stops, all you have to do is substitute a 25A fuse into the #1 position in the fuse block. If the blower starts, then you probably have a blown fuse (very unlikely if you use a 30A)..

If you are paranoid about the splices heating up, you can put a 20A ATA fuse in the new block and an 8A in #1 slot in the fuse block and split the current load yet still have a 28A fused circuit. Both are going to blow if you really have a dead short.

The problem with the failing fuses is the heating at the contact on the pointy end of those poorly designed fuses. The wiring is adequate for the current.

Doc Bill

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Bill, W8NTZ
Hillsboro, Ohio
1984 190D, 2.2, 5-speed
170K

Last edited by Cessna 195; 12-05-2010 at 12:21 PM. Reason: New, additional information
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  #2  
Old 12-05-2010, 05:33 PM
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Thanks for the write-up.

What are some symptoms leading up to this modification?

I have the same car and a squealing blower, but it works as intended.
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  #3  
Old 12-05-2010, 05:51 PM
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W201 blower fuse problem

Hi,
The problem first surfaced several years ago while in FL, the A/C crapped out in the middle of a 98 degree/99 percent humidity day. Totally mystifying until I found the blown (actually melted) fuse. Replaced it, no problem for several months, then same thing happened. This scenario was repeated several times and I noticed that the clip for the #1 fuse was discolored from heat. Etc. If you search the site for "blower fuse" etc. you will find countless posts lamenting the same problem. It is a poor design.

My solution, until I got it fixed yesterday, was to run the a/c-heater fan no higher than the #3 mark on the climate control and I didn't have any problems. But I sweat a little in the FL heat. Trailered the car to Ohio where I have the tools to work on it. Glad I did, EVERYTHING on it now works.

The squeaky motor is probably due to dry bearings. If they are dry, they are worn or are wearing rapidly. Taking the motor out is not impossible but it is not for the mechanically challenged. It CAN be removed without taking the wiper mechanism out as recommended on several posts/sites. Once I had the motor out, I saw some play in the bearings, so replacement was in order. **************.com has all the instructions and the motor. Photo's, tips, etc. Even supply a little tool to help get the plastic fans off the shaft.

Have you had the #1 fuse problem yet?

Doc Bill
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Bill, W8NTZ
Hillsboro, Ohio
1984 190D, 2.2, 5-speed
170K

Last edited by Cessna 195; 12-05-2010 at 05:51 PM. Reason: correction
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  #4  
Old 12-05-2010, 05:55 PM
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I see the source of the blower replacement was bleeped out. The place is source mercedes, reverse the order of the words, no spaces, and add dot com. Prices are fair considering you get a manual with photos and tips.

Doc Bill
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Hillsboro, Ohio
1984 190D, 2.2, 5-speed
170K
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  #5  
Old 12-05-2010, 05:55 PM
Registered Hack
 
Join Date: Mar 2008
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no, no fuses blowing yet except through my own fault when working on stuff.

I am new to this blower design.

When the bearings get worn enough, will it start shorting? Or will it make worse noises before that happens?
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  #6  
Old 12-05-2010, 06:07 PM
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Not likely it will short or blow fuses but the squeaking will change to a squall or howl and become louder, perhaps intermittently, as the bearings fail. It it gets loose enough that the fan would bind in the housing, it could blow a fuse but it would likely tear up the plastic fan turbine first. The evaporator coils are between you and the fan, so any pieces will get stuck behind there. It's not going to get better and if one goes to the trouble to get at the motor to oil it, why not just put in a new one?

You might look at the #1 fuse in the fuse block and see if the clip is discolored (normal color is a bright copper - over heated turns it dark brown and dull). Check and see if there is the recommended 25A fuse (blue) in the position. If you're lucky you won't have any problems but if it shows sign of over heating, it is a matter of time. MB recognized it and put out a "kit" to bypass the #1 fuse with a 30A. Looking at the pictures of the kit, it would be nasty to install.

Doc Bill
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Hillsboro, Ohio
1984 190D, 2.2, 5-speed
170K
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  #7  
Old 12-05-2010, 06:12 PM
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I recently replaced the fuse, it looked 'ok'.

So this mod is to fix the damage resulting from a failed fuse, or to prevent further failures?

Thank you again for all the info. Hope I didn't steal your thread.
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  #8  
Old 12-05-2010, 06:28 PM
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Join Date: Jul 2004
Location: Hillsboro, OH
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W201 blower fuse problem

The new fuse was to stop the failing MB fuse system so I could use the blower on full speed - like cooling the car down (it's the car that is stashed in FL). The blower motor replacement sort of fell in line with all the other problems. I had a leaking evaporator valve and was having to refresh the freon more and more frequently. To get at the evaporator valve, you are pretty much into the blower area anyway. It was squeaking and I thought it was the brushes. Got a set to replace them but when I got the motor out, the bearings were worn with some play in the shaft. And I only want to do this job once HAR HAR. So I fixed everything. It was always a crap shoot if I used the blower on full speed, even for a few minutes. It is no fun putting in a new fuse in the parking lot in the full sun!

Glad to help.

Doc Bill
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1984 190D, 2.2, 5-speed
170K
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  #9  
Old 12-05-2010, 10:48 PM
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Quote:
Originally Posted by Cessna 195 View Post
...

Yes, the wiring CAN be accessed from under the fuse block by removing the under dash kick panel. A (NAPA, etc) pigtailed replacement 30A fuse with the spade terminals (I think it is called an "ATA" type fuse) can be attached w/ one each yellow 10-12ga wire "splices". The supply end is a 2.5 (~12ga) black/green/white and the lead to the climate control (and blower) is a red/yellow 2.5 (or ~12ga).

The proper leads to attach to are not easy to identify however I used a telephone wire tracing device and put a 'signal' on each side of the #1 fuse block and picked the wire with the "hot" signal. It DID match the color codes given in the MB manual. The wires are not close to each other, but in separate wire 'bundles'. This is a little high tech for the usual week end DIY MB work but it CAN be done. You could do the same thing with a continuity checker and some insulation piercing probe tips.

There are a couple other wires under the fuse block with similar color markings, but they are smaller diameter. The nice thing about these press on splices, you can test and remove with little insulation damage if you pick the wrong wire.

A small ice pick like tool I made with a little hook on the end makes it much easier to pull out and isolate the wire of interest during this job. Yes, the fuse is hidden under the kick panel, but if the blower stops, all you have to do is substitute a 25A fuse into the #1 position in the fuse block. If the blower starts, then you probably have a blown fuse (very unlikely if you use a 30A)..

If you are paranoid about the splices heating up, you can put a 20A ATA fuse in the new block and an 8A in #1 slot in the fuse block and split the current load yet still have a 28A fused circuit. Both are going to blow if you really have a dead short.

The problem with the failing fuses is the heating at the contact on the pointy end of those poorly designed fuses. The wiring is adequate for the current.

Doc Bill
I agree, the fuses are poorly designed. I have found that the cheap Buss plastic aftermarkets are not as robust as the ceramic, but the latter are much more difficult to find. Thanks for the post, I have the same issue with the inability to run the blower full blast, even after replacing the blower with a very low-wear used unit. Not sure if I want to tackle the isolation of the leads for that circuit at this point. I am surviving with the blower on "high-medium."
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327K on 1986 W201, 602.911, 722.414 2.5 190D ("The Red Baron")
139K on 1993 W124, 104.942, 722.433 2.8 300E ("Queen")

http://farm5.static.flickr.com/4081/...0bb92d3c_m.jpg http://i370.photobucket.com/albums/o...g?t=1325284354

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.
- Albert Einstein

take a walk down memory lane...
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  #10  
Old 12-06-2010, 09:39 AM
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Location: Hillsboro, OH
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Hi Sasquatch,

The actual putting in the NAPA 30A pigtail replacement ATA fuse was about a 20 minute job ONCE the wires were identified. That's the hooker. I should have taken some pic's while I had the thing unbuttoned. If there is any interest, I can put a picture or two on the thread. You will need to positively identify the correct leads because there is another wire or two with the same color code (albeit smaller diameter). The 2.5 sq mm x-section wires are equivalent to US #12 ga so they are fairly easy to identify. Most of the other wires are smaller, like 14 to 20 ga.

Doc Bill
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Hillsboro, Ohio
1984 190D, 2.2, 5-speed
170K
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  #11  
Old 12-06-2010, 09:45 AM
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Already you have been of great help and I appreciate your diligence. Photographs would be icing on the cake. I like the 20+8 amp solution.
__________________
327K on 1986 W201, 602.911, 722.414 2.5 190D ("The Red Baron")
139K on 1993 W124, 104.942, 722.433 2.8 300E ("Queen")

http://farm5.static.flickr.com/4081/...0bb92d3c_m.jpg http://i370.photobucket.com/albums/o...g?t=1325284354

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.
- Albert Einstein

take a walk down memory lane...
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  #12  
Old 12-08-2010, 10:26 AM
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Location: Hillsboro, OH
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Hi Sasquatchgeoff

I have taken some pix however I am stymied getting them up loaded to the forum. If you will send me your email, I will send them direct to you. Mine: terrellmd@earthlink.net

If you know how to upload them to the thread, that would be great !

Doc Bill
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Hillsboro, Ohio
1984 190D, 2.2, 5-speed
170K
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  #13  
Old 12-10-2010, 10:37 AM
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Here are the pictures

Doc Bill

http://docterrell.com/blowerfuse.htm
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1984 190D, 2.2, 5-speed
170K
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  #14  
Old 12-10-2010, 09:19 PM
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Very, very helpful. I think I noticed a clutch pedal there - no? I would suggest updating your signature to reflect the vehicle(s) you own and engine/body/tranny configurations for reference when others in the forum look to contribute knowledge on your behalf.

Great job. I happened to get my hands on some OE ceramic fuses, looking forward to swapping those out over the holiday break.
__________________
327K on 1986 W201, 602.911, 722.414 2.5 190D ("The Red Baron")
139K on 1993 W124, 104.942, 722.433 2.8 300E ("Queen")

http://farm5.static.flickr.com/4081/...0bb92d3c_m.jpg http://i370.photobucket.com/albums/o...g?t=1325284354

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.
- Albert Einstein

take a walk down memory lane...
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  #15  
Old 12-11-2010, 07:56 AM
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OK, I can do that, thanks for the suggestion.

The hardest part was identifying the correct leads, but once that was done, putting in the splices was about 20 minutes worth.

Yup, it is a 5-speed, diesel, 2.2. Acceleration is like stepping on a grape. But it will wind up to 75-80, if given enough time.

Those ceramic fuses should work better. Be sure to clean the ends of the fuses bright and shiny as well as the contact point on the clips in the block. I expect they will still heat up due to the small contact area and the current.

Kent, at ************** dot com has some of the "brass" or more heat resistant fuses too.

Getting the cruise control amp overhauled by Peter at GDL, the actuator, etc., all checks out OK, heading back from Ohio to FL with the car in January.

Doc Bill
1984 190D, 2.2, 5 spd, 170K

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1984 190D, 2.2, 5-speed
170K
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