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  #1  
Old 06-26-2004, 12:15 AM
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Angry 94 e420 A/C blower just quit!!

My a/c blower was working perfectly, I turned off the car. Next time in the car there is no a/c fan. The compressor starts when the a/c button is pushed. The #7 fuse is good (this is the right one?) Is there a relay for the fan somewhere. Any idea of what could go wrong? The fan was working perfectly with no unusual noise or other symtoms. Any help appreciated..I'm in Phoenix and it is HOT!!!

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  #2  
Old 06-26-2004, 11:08 AM
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a/c blower

TTT Anyone have the climate control unit fail and cause this type problem. I don't want to buy one and find that it is not the problem. It is around $300.
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  #3  
Old 06-26-2004, 11:18 AM
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No, it is very unlikely to be a control unit problem.

The most common problem is the blade type fuse on the left fender ahead of the standard box. This is a special fuse and the current flow causes them to expand and contract till they crack from fatigue. That simple problem is probably most common, look carefully as it is often not obvious.

The next likely problem is the blower itself or the regulator below it under the windshield wiper assembly. There is good description in the archives on simple electrical testing at the three wire connector by the brake booster the verify whther the problem is in the blower are or in the control circuit.
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  #4  
Old 06-26-2004, 12:14 PM
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fuse

Thanks STEVE I will check that fuse when I get home. I didn't know there was an external fuse. I don't see it mentioned in the owner manual.

Chad
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  #5  
Old 06-26-2004, 12:22 PM
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The fuse Steve refers to is in a separate black housing about 2" long by 1" wide. Removing the cover will show a strip fuse with a screw in each end to hold it in place. I've blown mine and to make it work until I bought a new one, I soldered it together to have AC. With this temp. fix it can still blow but next to where it is soldered. Buy a fuse along with a spare to keep in your car.

Tobias MB
3 MBs
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  #6  
Old 06-26-2004, 12:33 PM
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Here is a picture from my 91 300e

Haasman
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Last edited by haasman; 06-26-2004 at 12:44 PM.
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  #7  
Old 06-27-2004, 12:13 AM
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Talking THANK YOU!!!!!!

THANKS TO ALL. iT WAS THE FLAT FUSE, WHEW, a/c!!!! You ARE ALL AWESOME!!!

I was afraid that it was something very expensive
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  #8  
Old 06-27-2004, 08:58 AM
LarryBible
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As suggested earlier, keep a spare fuse. It could be that the motor is getting worn out and starting to bind, increasing current, thus blowing the fuse.

If the fuse was bad due to stress as Steve described, it will be ages before you need to replace it. If it blows again soon, you will need to dig down to the blower motor and give it a spin. If it is not totally free, you will need to replace it.

Be prepared,
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  #9  
Old 06-27-2004, 09:57 AM
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I have only seen that fuse burned out twice. All the rest were cracked due to the expansion contraction thing.

The only reason I point this out is that I have also seen two wiring harnesses burnt for the same reason the fuses were brurnt and it wasn't the fan current.

The reason was that it is somehow possible to either get the wrong screws or tighten them to hard such that they wind up coming out of the plastic holder on the back side and ground on the fender beneath. Pretty rare occurance but the ones that burnt the fuses were just lucky cause the screw that touched was on the side after the fuse and just blew the fuse. The harness burns occured when the power side screw was the one involved.
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  #10  
Old 06-27-2004, 02:05 PM
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What is the rating of that fuse?

What is the rating of that fuse and where can I get them? Mine was cracked, not burned. I soldered it for temp fix as well.
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  #11  
Old 06-27-2004, 02:32 PM
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Most anyone servicing MBs will have them MB #00 545 20 34.
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  #12  
Old 08-29-2006, 08:16 PM
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Harness burned

This is a question for Steve Brotherton,

On my E420 The fuse was burned and one of the screws made it to the metal below the plastic housing. It was the screw toward the front of the vehicle. The nut was literally spot welded to the metal plate underneath. The harness was overheated but in my judgement the wire inside the harness is OK. Replacing the burnt fuse and degrounding the housing did not fix the blower problem

The question is, what is the consequence of the harness and wiring overheating and being grounded? So I can address my problem more intelligetly...
Thanks for your input...
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  #13  
Old 08-30-2006, 12:42 PM
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I have seen your situation occur a couple times. I think that both events occured due to loose screws and high local resistance causing heat which melted the plastic box till the screws touched the body. At that point the harness melted. One took a bunch of the harness with it. Once the screw hits the body the blower and controls are out of the circuit. Once the fuse is repaired, the blower can be diagnosed as usual.
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  #14  
Old 08-30-2006, 12:53 PM
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seems like this fuse should be a maintaince item...although it's funny.. i have two in my spare parts bin....and haven't replaced them...

maybe every 5 years or so...like a belt..

i think they were .35 each.
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  #15  
Old 08-30-2006, 01:04 PM
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Thanks all for the reply. I will try to repair it this weekend...

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