Troubleshooting Aux Fan - Page 2 - PeachParts Mercedes-Benz Forum

ah-kay · #1 10-06-2009, 03:10 PM

There should NOT be any heat in the first place if the contact is good. A lot of manufacturers have fuses made of plastic. Using ceramic fuse may eliminate the melting problem but not the heat problem. Good contact is fundamental to any connections, otherwise it will only get worse with burn marks and pittings.

Brian Carlton · #2 10-06-2009, 03:17 PM

Quote:

Originally Posted by ah-kay

There should NOT be any heat in the first place if the contact is good. A lot of manufacturers have fuses made of plastic. Using ceramic fuse may eliminate the melting problem but not the heat problem. Good contact is fundamental to any connections, otherwise it will only get worse with burn marks and pittings.

There's ample evidence on the forum that heat is definitely a result of high current across those fuses. The problem is so bad on the blower motor that M/B has a completely separate shunt to bring the power outside of the box.

Although clean contacts are certainly beneficial, the temperature issue with high current draw is not going to be eliminated.

ah-kay · #3 10-06-2009, 04:13 PM

Quote:

Originally Posted by Brian Carlton

There's ample evidence on the forum that heat is definitely a result of high current across those fuses. The problem is so bad on the blower motor that M/B has a completely separate shunt to bring the power outside of the box.

Although clean contacts are certainly beneficial, the temperature issue with high current draw is not going to be eliminated.

If I still remember my physic from University - heat is generated because there is resistance in the line. Power = I^2R. Power is dissipated as heat or other mechanical form. If R = 0 then there is no heat. Power = I ^ 2 (0) = 0. It could be a million Amp but there would still be NO heat, through the fuse or contacts. In otherwords, the fuse can be made of plastic and in fact most of them are.

Fuses are made of all kind of alloy, I would not limited myself to copper, bronze type of fuses as they are made to specification and it fits the application.

tangofox007 · #4 10-06-2009, 03:19 PM

Quote:

Originally Posted by phinsup

The odd thing is it doesn't actually blow the fuse it's melting the red plastic of the fuse rather then melting the fuse wire

That's a common issue with aluminum fuses. The aluminum oxidizes and insulates the connection, resulting in an increase in increased resistance and heat. Copper or bronze fuses will substantially eliminate the dissimilar metal corrosion problem.

ah-kay · #5 10-06-2009, 05:56 PM

FYI. Most if not all HIGH voltage transmission cables are made of aluminum. If it is good for power to the City, to your house. I really cannot see why it not good in your auto. It is the dirty contact which causes all the problem.

The posts we read in this forum are 'problem' posts. You do not hear success stories like 'I use aluminum fuses and I have no problem' post. I try to help the OP to resolve the heat problem and there is no need for me to debate with anyone on the merit of fuse elements material. You can use anything you can afford to buy, plastic, cermic, copper, bronze, aluminum, gold, silver etc. BUT keep the contacts clean.

tangofox007 · #6 10-06-2009, 06:36 PM

Quote:

Originally Posted by ah-kay

FYI. Most if not all HIGH voltage transmission cables are made of aluminum. If it is good for power to the City, to your house. I really cannot see why it not good in your auto. .

The issue is not whether aluminum is a good conductor of electricity. The issue is with the way that aluminum reacts with other metals it comes into contact with.

Quote:

Originally Posted by ah-kay

You do not hear success stories like 'I use aluminum fuses and I have no problem' post.

Maybe there is a good reason for that!!!

Here are a few words on galvanic compatibility:

http://www.engineersedge.com/galvanic_capatability.htm

ah-kay · #7 10-06-2009, 06:37 PM

Can some one help me to find some of these fuses made of copper, bronze or ceramic for newer cars? So it is a fallacy to believe plastic ones are cheesy ones.

The reason that these fuses are better is because the contacts are shape like a blade. Good contact = no heat. They still pose problems when the blades do not get a tight fit. I know b/c my 300SDL caught fire using one of this high rating fuse. I had a circuit drawing about 50A and the contact was loose but that is a story for another day. I carried a fire extinguisher, of course.

ah-kay · #8 10-06-2009, 10:53 PM

Quote:

Originally Posted by ah-kay

Can some one help me to find some of these fuses made of copper, bronze or ceramic for newer cars?

TangoFox and others? Do they exist or do I have to put up with the galvanic corrosion in my 2001 Town & Country minivan. The fuses have been good for the last 8 years but I am not so sure now.

fruitcakesa · #9 10-07-2009, 08:04 AM

My 240 fan kept melting the plastic bodied fuses, even scorching the card in the fuse box.
I cleaned the fuse holder and switched to ceramic/copper fuses and the problem is gone.

ah-kay · #10 10-07-2009, 11:48 AM

Quote:

Originally Posted by fruitcakesa

I cleaned the fuse holder and switched to ceramic/copper fuses and the problem is gone.

May be I am more inquisitive/logical than others. What fixed the problem? Cleaning the fuse holders, switching to ceramic or switching to copper fuses or all of the above? There are 6 combinations if my permutation math is correct.

May be that is the reason plastic fuses get such a bad rap. It was never the root of the problem but a percieved problem.

fruitcakesa · #11 10-07-2009, 12:48 PM

Specifically I don't know what did the job. However, it seems to me that, all elements within the electical path should be in optimal conducting condition in order to have the most efficient power use and least electrical resistance ie; less heat produced

bobodaclown · #12 10-07-2009, 03:12 PM

10-15 + year old fuses will end up with some corrosion. Use quality ATS ceramic fuses (Torpedo style). You'll be better off in the long run.
http://www.littelfuse.com/data/en/Data_Sheets/Littelfuse_Fuse_ATS.pdf

nomorehurry · #13 09-01-2010, 05:40 PM

Fan fuse, D***, D***

FWIW I just spent many hours and a significant amount of dollars replacing parts that didn't need to be replaced because of the D*** fuse. It was one of the first things I checked, and it looked whole and complete. No problem there! Well, after nothing else worked, and I was trying to figure out how to wire it directly to the battery so it would run but shut off when the engine was turned off, I took another look at the fuse. It still looked good, but I remembered the post about plastic fuses. When I took the fuse out, the metal strap was good, and the plastic holder was good, but the area around the connection where the aluminum and copper meet had heated and the plastic melted just enough to block the connection. It could not be seen except when the fuse was removed! The only indication was some brown (burned?) plastic on the lower portion of the fuse; not even enough to cover the nipple where it joins the copper bracket.
But it now works, and as soon as I get to the Volkswagon dealership, I will buy all new fuses and put them in. (

Volkswagon - because german parts is german parts.)

So even if the fuse looks OK, try replacing it with a new one.

Many thanks to all who posted on this thred!!

phinsup · #14 09-01-2010, 09:07 PM

Mine kept blowing fuses, I ended up rewiring the whole thing. Basically ran a relay to the battery and the coolant temp switch to the relay. Although in south florida i'm not sure it matters, fan runs unless i'm on the freeway anyhow.