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  #1  
Old 06-14-2011, 05:09 AM
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My E300D a/c fan is dead

Good day.

A few weeks ago, I stared noticing that my A/C fan was making strange noises when I braked or went over bumps. This past weekend, while driving along, the fan unit stopped altogether. It's as if there is no power on the console.

I checked the fuses, (fuse #7 I believe), but no blown fuses. I'm sure the A/C is running as I can feel a very small amount of cold air coming out of the vents while the car is moving.

So, where do I start trouble-shooting this problem?

Thanks in advance,
Bjoern

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Bjoern

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'08 E320 Bluetec - 101k
'95 E300 Diesel - 241k
'92 300D 2.5 Turbo 321k (Rear-ended by negligent driver and totalled)
'06 Jetta TDI (Sold in 2010)
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  #2  
Old 06-14-2011, 08:16 AM
Diesel Preferred
 
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First, you need to make sure you're push button unit is sending a signal to the blower motor voltage regulator. If that signal is present, then pull the blower motor, clamp it in a vice and apply 12v to see if it turns. If it works, then the voltage regulator/controller for the blower fan is probably dead.
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'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
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  #3  
Old 06-14-2011, 08:30 AM
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Check for a blown fuse in the "blue" low speed relay in the back section of the fuse box.
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  #4  
Old 06-14-2011, 12:17 PM
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If yours is a W124 - check the 30 amp strip fuse that is located just outside the fuse box, that part is like 50 cents at NAPA if they have it in their shop.
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  #5  
Old 06-14-2011, 02:43 PM
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If it was making noises you can get a lot of spare fuses or cut to the chase and get a replacement motor.

Sixto
87 300D
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  #6  
Old 06-15-2011, 12:07 PM
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Quote:
Originally Posted by mbdoc View Post
Check for a blown fuse in the "blue" low speed relay in the back section of the fuse box.
Thanks for the hint. I pulled the relay, checked the fuse and using a 12V supply, confirmed that the relay operates properly.
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Regards,
Bjoern

_________________________________
'08 E320 Bluetec - 101k
'95 E300 Diesel - 241k
'92 300D 2.5 Turbo 321k (Rear-ended by negligent driver and totalled)
'06 Jetta TDI (Sold in 2010)
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  #7  
Old 06-15-2011, 12:42 PM
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The blue relay with fuse is for the aux fan low speed, but you say that the blower does not work?

the blower is fused through the 30 amp strip fuse.
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  #8  
Old 06-15-2011, 04:37 PM
winmutt's Avatar
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Quote:
Originally Posted by sixto View Post
If it was making noises you can get a lot of spare fuses and a fire extinguisher or cut to the chase and get a replacement motor.

Sixto
87 300D
There fixed it for you.
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  #9  
Old 06-15-2011, 04:52 PM
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Quote:
Originally Posted by Zulfiqar View Post
The blue relay with fuse is for the aux fan low speed, but you say that the blower does not work?

the blower is fused through the 30 amp strip fuse.
Hi Zulfiqar, this strip fuse you mention, is it right next to the fuse-box?
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Regards,
Bjoern

_________________________________
'08 E320 Bluetec - 101k
'95 E300 Diesel - 241k
'92 300D 2.5 Turbo 321k (Rear-ended by negligent driver and totalled)
'06 Jetta TDI (Sold in 2010)
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  #10  
Old 06-15-2011, 04:55 PM
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Hi all.

Does anyone have the electric circuit diagram for the 1995 E300D Model 124.131 A/C system? I have some poorly scanned images but none of them is for my particular model.
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Regards,
Bjoern

_________________________________
'08 E320 Bluetec - 101k
'95 E300 Diesel - 241k
'92 300D 2.5 Turbo 321k (Rear-ended by negligent driver and totalled)
'06 Jetta TDI (Sold in 2010)
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  #11  
Old 06-15-2011, 09:26 PM
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Quote:
Originally Posted by bhehmann View Post
Hi Zulfiqar, this strip fuse you mention, is it right next to the fuse-box?
The strip fuse is right in front of the main fuse box - its inside a little casket type housing with thick black wires, by looks it will seem intact - remove the screws and it will be in 2 pieces.

my miserable MB dealer wants 7 dollars for one - NAPA has it listed for 50 cents on their site. when mine blew I just ordered 2, put one in the car and one is in a little box of spare fuses I have in my car
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  #12  
Old 06-15-2011, 10:12 PM
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Good evening.

Thus far, I've determined that the blower motor is ok. I measured the voltages on the regulator as follows:

Multimeter negative probe on black tag.

Fan set to high, A/C off, 0V on red and yellow tags. (expected).

A/C set to EC, normal, Bi-level or defrost, 9.5V on yellow, 0V on red, 0V on red/blue blower leads.

This means I'm getting 9.6V from the Automatic Climate Control Unit (yellow), but nothing from the F15 Auxiliary fuse holder (red), right?

Where is this F15 fuse?
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Regards,
Bjoern

_________________________________
'08 E320 Bluetec - 101k
'95 E300 Diesel - 241k
'92 300D 2.5 Turbo 321k (Rear-ended by negligent driver and totalled)
'06 Jetta TDI (Sold in 2010)
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  #13  
Old 06-15-2011, 10:59 PM
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F15

Here it is: the rectangular black thing next to the shock absorber top. The fuse is inside, a strip of aluminum rated at 30 Amps. NOTE: these strip fuses are also available in 50 and 80 Amp versions, make sure you get 30 Amps for the blower. Also make sure the connections are clean and tight. You might even want to use a little of the stuff electricians use when they're joining copper and aluminum wire, to prevent corrosion.


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  #14  
Old 06-16-2011, 05:23 PM
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Thanks to you guys, I found the the elusive fuse. Interestingly, the fuse was broken instead of the typical melted and blackened appearance after a typical blow-out.

I did check the blower, it ran well when I applied 12V directly, no play on the shaft and the commutator looked fairly clean.

I will purchase 2 fuses and seen what happens.

Thanks again,
Bjoern

PS. Had one hell of a time trying to replace the rubber on the bottom of the windshield........
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Regards,
Bjoern

_________________________________
'08 E320 Bluetec - 101k
'95 E300 Diesel - 241k
'92 300D 2.5 Turbo 321k (Rear-ended by negligent driver and totalled)
'06 Jetta TDI (Sold in 2010)
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  #15  
Old 06-16-2011, 05:27 PM
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good you found it.

and yes that fuse is quite a character it cracks and sits there defying you until you press it with something.

I had a VW diesel and a similar but 50A fuse was employed to protect the glow plug harness - and this thing was upside down mounted below the weatherstripping, And typically it would blow when you are 1000 miles from home in the middle of the desert in dead cold weather.

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