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  #1  
Old 11-19-2017, 01:11 PM
Knappy Drag Racer
 
Join Date: Jun 2008
Posts: 1,725
W124 300TD 300TE blower motor fuse location

Hi all. I did a search using the exact same words that make up the title of this thread. Didn't find anything relevant. I always try hard not to start new threads. Maybe I can get a pass this time? Anyways, I'm talking about the blower motor fuse that is normally on the left side strut tower. Benz, in their infinite wisdom felt the need to relocate this thing on the wagons. The subject car is the '87 300TD that I recently purchased from fellow board member benzguy300. (He's a pretty knowledgable guy but he doesn't know where it is either.)

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89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.
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  #2  
Old 11-19-2017, 01:33 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,841
IIRC the external 30-amp strip fuse is a retrofit to ‘87s. If you don’t see an external fuse holder, it’s probably still running off the 16-amp fuse in the main fuse panel.

Sixto
98 E320s sedan and wagon
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  #3  
Old 11-19-2017, 03:03 PM
Diseasel300's Avatar
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If you searched for a "moter" fuse, that's probably part of your problem. The 126 had the fuse moved externally somewhere ~June 1986, so the very last of the '86es and all '87's have the external fuseholder. I'd expect the W124 to be similar. Look for a plastic "box" somewhere in the wiring bundle near the fuse box. My '86 has the external fuse and has the location in the fusebox card crossed out with magic marker. Mine's after the VIN change, so I can only assume that was a factory "feature".
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  #4  
Old 11-19-2017, 03:10 PM
Knappy Drag Racer
 
Join Date: Jun 2008
Posts: 1,725
Quote:
Originally Posted by sixto View Post
IIRC the external 30-amp strip fuse is a retrofit to ‘87s. If you don’t see an external fuse holder, it’s probably still running off the 16-amp fuse in the main fuse panel.

Sixto
98 E320s sedan and wagon
Well first of all I have to say that it is VERY nice of you to help me with this considering the fact that you were next in line to get this car! Thanks!!!

There was only one fuse in the box that was bad, the "C" fuse. The list of stuff that it serves is long, but none of them have anything to do with the climate control system. It's an 8 amper, so I replaced it with another 8 amper which it promptly blew, so I replaced it with a 25 amper with the same result. So we definitely have issues there but I'm gonna have to let those go for now. Right now I need that blower motor. At location 12 it says "blower motor" so I rotated that fuse to re-establish a good connection but it didn't change anything. I also rotated #7 cause that one feeds the blower motor temp sensor. Still nothing. Where should I go next?

Again, thanks for your help Sixto!
__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.
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  #5  
Old 11-19-2017, 03:14 PM
Knappy Drag Racer
 
Join Date: Jun 2008
Posts: 1,725
Quote:
Originally Posted by Diseasel300 View Post
If you searched for a "moter" fuse, that's probably part of your problem.
Geeze, what a screw-up. I know how to spell "motor". Thanks for bringing this to my attention. Does anybody know how to edit the title of a thread?

I've looked extensively for an external box and so did the P.O. We just can't find anything.
__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.
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  #6  
Old 11-19-2017, 03:22 PM
Knappy Drag Racer
 
Join Date: Jun 2008
Posts: 1,725
I just performed another search with the correct spelling. The only relevant thread that came up was this one.
__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.
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  #7  
Old 11-19-2017, 03:24 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,841
Is there power to the ACC at all? Do you hear the aspirator motor or vent pods as you switch modes? IIRC the wires to the porcupine go through a junction block by the cowl beside the brake booster. Power, ground and a yellow(?) signal wire. This is from the deep recesses but the signal is 0-5V or 0-7V which the porcupine translates to a PWM signal to the motor. I’d start at that junction block.

Sixto
98 E320s sedan and wagon
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  #8  
Old 11-19-2017, 06:09 PM
Knappy Drag Racer
 
Join Date: Jun 2008
Posts: 1,725
OK, I'm not getting any vacuum sounds at all but maybe that's because the car hasn't run in over a month, leaving me with no reserve vacuum to operate stuff. I can't start it right now because the ALDA is off for adjustment and I don't want to put it back on until my back is a little better. (I can support myself a little better when working in the fender area where this blower motor wiring stuff is.)

In poking and looking around for that junction block I'm not finding anything that fits your description except for a block that is on top of the bulge that is behind the brake power booster. Could that be it? I don't want to be tugging on anything unless I'm sure it is what I'm supposed to be tugging on because everything that is plastic or rubber just crumbles apart on these old cars that live in the heat and smog of So. Cal. This car is no exception. So is that plug on top of the bulge the one? For sure?
__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.
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  #9  
Old 11-19-2017, 09:44 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: Eastern TN
Posts: 20,841
I think you’ve got it - Mercedes-Benz W124 HVAC Resistor Replacement | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article

Your engine will start and run fine without the ALDA. You might see more smoke when you go heavy on the pedal and shifts might be harsh but it won’t matter if you’re just testing the AC.

Sixto
98 E320s sedan and wagon
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  #10  
Old 11-22-2017, 05:33 PM
Knappy Drag Racer
 
Join Date: Jun 2008
Posts: 1,725
Holiday stuff is interferring with progress here. I'll have to pause for a bit. In the meantime, if anybody else can think of anything else that needs to be looked at, please post it. Thanks!
__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.
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  #11  
Old 11-22-2017, 06:13 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
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Location: Mount Holly, NC
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Send jay_bob a pm... he is fantastic at the electrics on the 124.

Oh, and I’ll edit the title for ya...
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My drivers:
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  #12  
Old 11-23-2017, 08:34 AM
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No need for the PM, I’ll be glad to help right here...

First here is a web link to all maintenance manuals for the 124:
Mercedes Benz Model 124 - OM602, OM603 Maintenance Manuals

Second if you go to chapter 83 this is where all the climate control system info resides.
83 Climate Control System

Somewhere out there is a TSB on replacing Fuse 12 in the box with an external strip fuse.
Found it: http://w124-zone.com/downloads/MB%20CD/W124/w124CD2/Program/Chassis/54-0180.pdf

This shows where the external fuse is located.

Note that fuse 7 powers the climate control unit electronics. If the fuse is dead then nothing will work. There is a troubleshooting procedure for the climate control electrical system here:
http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Climate/83-604.pdf

Note this procedure calls for a special test adapter that goes in between the wiring harness and the CCU. However you can get by without this if you get a copy of the wiring diagram
http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/ETM/ETM.pdf

Make a printout of the procedure and a printout of the pages for the climate control electrical system, and at each step of the procedure, it will tell you which circuit it is trying to test. The referenced points will be the proprietary test box in the procedure, but if you look at the wiring diagram you can see which 2 points they are trying to check at the connector going into the CCU. Make a note on the printed copy of the test procedure at each step where you will have to make your check of the pins on the vehicle connector.

Now you’ll want to get a voltmeter and run through this test script.

The air diversion doors work on vacuum. Since this is a Diesel engine you do not have manifold vacuum, so there is a vacuum pump at the front of the engine. The factory setup for the climate control vacuum is off the tap on the top of the vacuum pump. This is the same place where everything else vacuum related taps off (except the engine shut down, which taps off the brake booster line). By default this is a green hose. It goes along the side of the engine block and passes into the area where the brake booster resides. There is a coupling to another green hose into the cabin. Make sure this coupling is good. If you lose vacuum, then the air will always blow only out the defroster vents.

Post back with what you find if you need more help.
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both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

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1987 300TD sold to vstech
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  #13  
Old 01-27-2018, 10:07 PM
Knappy Drag Racer
 
Join Date: Jun 2008
Posts: 1,725
Quote:
Originally Posted by vstech View Post
Send jay_bob a pm... he is fantastic at the electrics on the 124.

Oh, and I’ll edit the title for ya...
Thanks! And thanks for the edit!

Quote:
Originally Posted by jay_bob View Post
No need for the PM, I’ll be glad to help right here...

First here is a web link to all maintenance manuals for the 124:
Mercedes Benz Model 124 - OM602, OM603 Maintenance Manuals

Second if you go to chapter 83 this is where all the climate control system info resides.
83 Climate Control System

Somewhere out there is a TSB on replacing Fuse 12 in the box with an external strip fuse.
Found it: http://w124-zone.com/downloads/MB%20CD/W124/w124CD2/Program/Chassis/54-0180.pdf

This shows where the external fuse is located.

Note that fuse 7 powers the climate control unit electronics. If the fuse is dead then nothing will work. There is a troubleshooting procedure for the climate control electrical system here:
http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Climate/83-604.pdf

Note this procedure calls for a special test adapter that goes in between the wiring harness and the CCU. However you can get by without this if you get a copy of the wiring diagram
http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/ETM/ETM.pdf

Make a printout of the procedure and a printout of the pages for the climate control electrical system, and at each step of the procedure, it will tell you which circuit it is trying to test. The referenced points will be the proprietary test box in the procedure, but if you look at the wiring diagram you can see which 2 points they are trying to check at the connector going into the CCU. Make a note on the printed copy of the test procedure at each step where you will have to make your check of the pins on the vehicle connector.

Now you’ll want to get a voltmeter and run through this test script.

The air diversion doors work on vacuum. Since this is a Diesel engine you do not have manifold vacuum, so there is a vacuum pump at the front of the engine. The factory setup for the climate control vacuum is off the tap on the top of the vacuum pump. This is the same place where everything else vacuum related taps off (except the engine shut down, which taps off the brake booster line). By default this is a green hose. It goes along the side of the engine block and passes into the area where the brake booster resides. There is a coupling to another green hose into the cabin. Make sure this coupling is good. If you lose vacuum, then the air will always blow only out the defroster vents.

Post back with what you find if you need more help.
Thank you so much for all of this help and info! I'm sorry I left this thread hanging for so long, but I've entered another nightmarishly busy period in my life. This car is not helping either. Right after my most recent post in this thread, it started giving me another trouble. It now acts as if it's starving for fuel after it has been driven for about 15 to 20 miles. Good times! Solving that issue obviously takes priorety over this electrical stuff, but I just flat have no time for either right now. After I check the obvious, like filters and the sock/screen in the tank, I'll research the info here, and if I still can't solve the issue, I'll start another thread about it. I always keep a tab open on Peach Parts to remind me to check in here, but I'm just so busy right now! Again, I'm sorry.

Years ago, as my beloved AMCs got too old to remain practical as daily drivers, I had to reluctantly move on to other cars. I fear that I am once again facing that old crossroad in my life, as my W124s are demanding too much of my time! They are perfect for a guy whose kids are grown or for a younger guy or gal who doesn't have kids yet, but for me, an older guy who unfortunately got a late start on the family thing, they are becoming a headache!

Regards,
Eric

__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.
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