blower fuse started a fire in my engine compartment!
 

I was driving down the road today in my '93 400E with my A/C on and my blower "hiccuped" for a second. About a minute later I was slowing down at a red light when I noticed smoke coming out from the drivers side of the hood. I immediately pulled into the turn lane with my flashers on and turned off the blower fan. I popped the hood and the blower fuse was completely gone and all of the plastic around it was on fire. :eek: I blew it out after a couple tries. The hood pad even melted. What should I do? I'm afraid to even try the A/C now.

This has got me worried because the '88 300E I sold to my neighbor had the same thing except the only thing the fuse melted was the plastic cover that goes over the fuse.

I saw this melted fuse/hoodpad earlier in the day, and it looks as bad in person as it does in the picture...maybe worse. If I wouldn't know any better, I would say the plastic fuse holder erupted like a mini volcano.

The only theory that I have so far, is that there was a hairline crack...seeing as how there is so much current, it was able to bridge this hairline crack, and at the same time because it was bridging this gap, the metal started to heat up/ turn red, which then caused the subsequent melt-down.

Or....a cockroach was sitting on the metal strip, and when the current went through he hung in there for a while until he finally blew up, and what you see it actually cockroach guts.

I think I will stick by my first theory, and see what y'all come up with. I have a keen interest in knowing the cause, since I have a '94 E420.

-Larry

*** bump ***

At the risk of annoying anybody...

I would really like to know if anybody has had this happen - I have a E420 and would like to know if there is something that I can do to prevent this from happening to me.

I am sure that other 400E/E420 owners wouldn't mind preventing fires under the hood as well.

thanks! - Larry

I would guess that if the fuse was the right size and did not blow, than the fire/heat was on the line side of the fuse. Maybe you had a bad connection from the wire to the fuse spade, or between the fuse holder and the fuse spade. The fuse would not blow in this case.
If the fuse did not blow, make it blow on purpose using a jumper wire from it across the battery. Just to make the sure the fuse blows. If it blows, then I am certain you had/have a loose connection of some sort on the line (battery) side of the fuse.

My independent mechanic told me that he originally suspected that my blower motor had frozen up and that caused the subsequent fuse to blow/fire. He has since taken my blower motor out and verified that the motor was not bound up.

When the initial blower "hiccuped" I know for a fact that the blower was still running even while the fire was burning. After I saw the smoke, I turned the blower fan off and then after putting my flashers on, I turned the car off and popped the hood. After extinguishing the fire, I started my car up and of course since there was NO fuse the blower motor did not run. Does fire conduct electricity? Although, there was NO fuse while the fire was burning, I KNOW the blower motor was running.

Anybody know if fire will conduct electricity?

tkamiya,

Thanks for your reply. I did not assume that you were accusing me of anything. As a matter of fact, my independent mechanic replaced that same blower motor fuse about 6 months ago. That time, however, it was merely that the fuse blew and the blower motor quit. I know he put in the right fuse because I watched him install it. That is the only reason I knew that the fuse area was on fire when I originally had the problem. The blower motor "hiccuped".

Thanks again. Sometimes it is frustrating on this forum because you can ask a question AFTER you have searched the archives and yet still nobody answers your post. Not even to say "hey, I feel for you. Same thing happened to me."

Blower motors are nasty little creatures sometimes! When they go bad they will start pulling amps like gangbusters and if you have any problem whatsoever in the circuit where it can pull from, it will. If the circuit has a weak point it will heat it up. Not easy to tell exactly what happened without seeing the actual spot where it erupted, but I have seen some of those auto fuses heat up before and melt to the point the 2 poles connect together, this would create the weak point, or the failure. It is not the fuse or the circuit, but more likely the blower motor going bad and drawing too many amps. I feel bad for you because it is likely you will have to replace your whole fuse block. When you buy a car, always look in the fuse block, check the fuse sizes to the specified size on the chart and make sure no funny business is going on in there. The fuse should have stopped the motor, you had a very rare unfortunate incident. The fuse block has a lot of wires in there. If you are not comfortable replacing it, get someone else to do it. Did you open the lid to the fuse box yet? It looked as if it were still closed? What about the big fuse and relay box behind it? You have a lot of work to do, you will have to replace your blower motor and likely the harness to it, also you very likely could have a problem with your climate control assembly. Good luck!
Brian

That is probably more likely than my theory, I don't know a lot about he E class cars, I didn't know it had a fuse link independant of the fuse block, That is good news though as he will only have to replace that link and not the whole block. Thanks !
Brian

I've seen this and there was a very simple cause. One of the screws that held the fuse was either too long or overtightened till it hit the fender under the holder; taking the power side right to ground. Bang!

A bit of an update (I went to the mechanic that is working on fz500sel's E400).

Seems it was something in the ignition switch that caused the fire. I looked at the removed switch, and noticed that X15 was broken.

What is this connected to, that would cause a fire?

Weird....

Fuse fire on my w124
 

Hello, your post is of great interest to me as this has just happened to our 1990 300E. Under hood, after the fire looked similar. We put the fire out with a blanket. We have had the paint work repaired. We have wired in anew 30 amp fuse, the type most new cars have, not mercedes fuse link, and the fan at any speed continues to work and not blow the fuse. The fire was caused directly by MB fuse due to its location. It, and it alone, started the hood material on fire,including other wires to catch on fire. With the hood closed it more or less touches the hood lining.
I have no trouble with fuses blowing due to any cause.The fuse is supose to 'burn out'> Its sole perpose is so that wires/cars do not burn to the ground. Right? I do have a big problem with M.B. over this 'add on' fuse link. It was an quick fix for the earlier smaller fuses in the fuse box. Do you know of a good law firm? My pictures are the same. let me know what you think please. warm regards........miglenda

fuse fire-miglenda
 

Hello Larry, thank for the link. In our case the fuse was red hot and did not to what a fuse should do. It ignited the hood liner. After the fire was put out and our B.C.A.A. towed the car first to our home prior to phoning our insurance company. At home I started the car up, hood open, and it again was started arking and spitting small fames. It never melted the plastic holder!
Just the arking from it created the other fire. your thoughs. Maybe a small debt court would help us all out?.

regards
michael---miglenda

fuse fires
 

Hello Brian,I have a post under miglenda-fuse fire. Our car is as new through out and under the hood is spotlessly clean. This inline type fuse was stock and nothing in its mounting shorted it out. I acutally saw it arking through the plastic connector. The fire was caused due to its mounting on the shock tower. When your hood is closed your hood liner is is more or less just about touching it. It should get hot and burn out, not keep arking and burn the car down. It is none other than a bad design and location. We have a large fleet of Hwy trucks and from time to time fuses burn out. Some bigger than 30 amp. Never has a fire been started due to this.They were mounted properly.
regards
michael.

I've seen this a number of times. In all cases the problem was either a wrong too long screw on the feed side or a continued disreguard for a high resistance connection till the point where the heat allowed the circuit to melt down allowing the screw to touch the body on the feed side.

Tight clean connections of original specification have no problems even with shorted components. The fuse will blow.

I am wondering......
 

Has anything like this ever happened on a W126, (concerning the blower motor), or are they setup different that the E-Class?

I know there has been issues with "leaf buildup" under the fuse box of a W126, which I am about to start another thread about.

AS Steve stated, problem with previous repair.

Retaining screw too long OR using a GLOW system fuse rated at 50A or higher!

Have seen the same problems with the W126 chassis from 1986! CHECK the fuse rating & make sure that ONLY a 30A fuse is used.

Stevebfl
MBdoc

Stop beating your heads against the wall.:D

I had my fuse burn out, and noticed the following
 

I believe that this is a poor design more than anything else. Fuses are not only rated by their amps, but whether they are 'slow burn' or 'fast burn'. This is really a fusable link, and designed for 'slow burn'. It really shouldn't be! If there is excessive current draw on the blower motor, the fuse should pop right away.

My fuse burned without starting a fire, but the plastic housing was melted due to the heated slag of the fuse material. Also, upon close inspection of the material, the fuse link had obviously heated to the point of a metal fire and was severly oxidized and liquified.

I'm going to replace mine with a circuit breaker.

fires + cars scare me. I have a 93 190E is this somthing i should investigate...I mean so far I havent seen anything to indicate a problem of this level. We drove it 10hrs (VA to OH) with the A/C on and the only thing we experienced was a "white smoke" that came out of the vents for a little while...it had no odor to it once so ever. It only lasted for maybe 15 minutes.

glad to see no one got hurt.

Don't really seem like its an issue on the 190E... most cases seem to come from the "E-Class" chassis.

I do not think that white "smoke" is cause for concern, as far as electrical goes. I do not recall what make of car it was, but my aunt had a car that did this once and the mechanics told her it was condensation. It only did it occasionally. I think it is more like moisture/condensation. Just make sure it does not smell electrical.

If fire concerns you , I suggest you do what we do.... carry an auto fire extinguisher. We carry them for safety in ALL of our cars. Heck, in one car, I have two of them. The extinguisher in my dads car saved a car (not ours) that was on the highway from a potential major fire. He "thought fast" and disconnected the battery, then sprayed it with the extinguisher. Luckily only minor damage to that car. What had happened was that someone had miswired a generator (was a 50s car) and it had severely overheated and set the wiring harness from the generator ablaze. :eek:

cdplayer
 

I just bought a 1984 126 and drove it 700 miles home with no problem. But one Sat. while checking the AC operation under the hood a small fire erupted just under the brake master cylinder. As it turned out this car had been parked under trees. And a bunch of leaves had collected in a space behind the engine and in front of the firewall. Well, over time these leaves became compacted and eventually collected near the blower resister. The resister is a metal box like a big piece of swiss cheese with four springs inside it. It was the springs that glowed red hot that ignited the leaves. Lucky for me the car was idling in my drive way when the heat generated by the resistor finally caught the leaves on fire. No damage though. I replaced the resistor and the blower motor too. I used a strong shop vac to remove the debris. Now all is well.
Just thought I would bring this up. And for everyone to take a closer look at the small space under their brake master cylinders.

I am going to have to clean out under that on my 85'. I have tried to use my hands, but that is impossible. Very poor design if you ask me.

check this out.... :eek: .....any relation to this thread ?

This is very common problem....as per the above explaination.
Fuse material corrodes in contact with screws....this causes high resistence...couple this with high amp draw from a failing blower fan and heat enough to allow holder to melt . ....sometimes this heat is enough to ignite the plastic.

In every service on vehicles so equipped, I have checked blower amp draw to prevent loom damage .

Fuse would be better if suspended....then fuse strip should blow.
Have often found 80 amp strips used in this location bent up as they are longer than the holder.






.

I have had the same issue with meltdown a while ago and about to do the repairs now. My problem is that after the fuse housing burned, I lost the +12 at the fuse leg, which goes inside the car into a bundle (to the ignition switch?). Has anyone experienced the severage of the +12 connection?

I have been driving the car for six months now without wiper or AC.

For repair of the +12 leg. What would you recommend?
BTW, mine has the cabin filter which may have caused the whole issue as Steve mentioned above. So, I would say replacement of cabin filter is a good maintenance item to keep.

+12V line repair question
 

I have had the same issue with meltdown a while ago and about to do the repairs now. My problem is that after the fuse housing burned, I lost the +12 at the fuse leg, which goes inside the car into a bundle (to the ignition switch?). Has anyone experienced the severage of the +12 connection?

I have been driving the car for six months now without wiper or AC.

For repair of the +12 leg. What would you recommend?
BTW, mine has the cabin filter which may have caused the whole issue as Steve mentioned above. So, I would say replacement of cabin filter is a good maintenance item to keep.

+12V Repair Q
 

OK...

Let me rephrase, to make the answer simpler.

Is there a +12 (past ignition switch) terminal under the hood that I can access and use for my power on the blower?

If not, I know how to get +12 that's not connected to the ignition switch where power would be on constantly. Is there harm in doing so?

Thanks for your help. I am not in a big rush to finish, but it would be nice to put things back together soon...

Yasser

sorry to butt in but have you considered that the fuse that fits in the little holder looks the same whether it's a 30 amp,50amp or 80amp.i have read the whole thread and my guess is that the original blown fuse was replaced with probably an 80amp[glow plug] fuse and a worn blower motor drawing too many amps[tight bearings]caused the little fuse holder to heat up and because of it's placement in the 124 body as it melted one of the screws dropped and touched the body and caused more heat and voila! if the correct fuse had been in there it would have popped long before enough heat to cause the problem.someone who didn't know any better went to box of spare fuses,saw what looked like identical fuse and put it in and the blower worked not realising that it was a fire waiting to happen.suggest that you all go to your fuse holders and check the amperage on the fuse.of course the next time that someone fits a wrong fuse instead of replacing the blower motor[too many dollars and what harm will a bigger fuse do anyway] will not be the first time.

I am having this problem right now actually. My blower motor was working fine until one day it stopped and I thought I blew a fuse. Looked in the fuse box and the fuse was melted, but the copper was not broken. At first I attributed it to an older fuse and oxidation, so I went out and bought some new ones and rewired the box to move the blower motor fuse to an unused slot. Worked for about 3 hours and the same thing happened. I thought it must be oxidation on the connectors for the wire leading to the blower motor, so I clipped the ends off and wired in an after market inline fuse outside of the box. I started up the car, turned on the AC and monitored the fuse temp for about 5 min, at which point it got too hot to touch. I have a new blower motor that I am going to try to put in tonight so we'll see if that fixes the problem, but I'm a little concerned that a 25 amp fuse will actually MELT before it blows out (I believe they are 25 amps, but I could be mistaken).

Oh, the car is an 86 300E that I've had for a little over 8 years.

This is a 30 amp blade type fuse, not 25. You can monitor the current drawn by the blower motor using a clamp amp meter if you have one available.

I agree, no matter what was at fault the fuse should have blown. That is what they are designed for. As long as everything is kept orderly and to manufacture specs this should never happen. :D

This Just happened to me I could not believe it. I was driving 60 mph on a crowded free way when my car shut off by its self I pulled over immediately next to a wall and traffic inches away. I noticed the smoke coming out of my hood. I opened it and flames were erupting out I put the fire out as quickly as I could by blowing it out. Two minutes latter a Miami Dade police officer stopped ask me if everything was okay I told him what happen he asked me if everything was under control and told him I just called a tow truck he said okay and left (he was a worh less). Florida highway patrol saw me and stopped to protect me from the traffic flying by inches away. When a semi truck almost slams into me slamming his breaks witch looked up and almost causing a major accident. At that time the officer and I almost crapped ourselves and decided to move the car to the far right he turned on his lights and pushed my car with the patrol car to cross all 6 lanes of heavy fast moving traffic.
It could have been a lot worst I could have burn to death. Luckly I was the only one in the car.
I called Mercedes to file a complaint they told me that they would contact me back and took a report.
If this happened to you please call 1-800-FOR-MERCEDES (1-800-367-6372)
I wanted to know how many people this has happen to.
I believe there should be a recall if it is happing to a lot of people because it could cost someone’s life.

There is a very timely article in this month's Star Magazine about fire safety and the recommendation for keeping a fire extinguisher and other life-safety equipment inside the vehicle.
Cheers,
Jeff

Some of the W126s were upgraded in the field because of fires and damage to the fuse block and wiring due to heating of the terminals for the blower fuse: the blower draws a lot of amps when on HIGH, and that happens a lot here in the South; the terminals get hot due to resistance, even though the current is not enough to blow the fuse. The plastic fuse block holder turns loose of the terminal and the hot side contacts something grounded or another wire, and POOF. In my case, I was going down the Interstate, when white smoke started pouring from under the instrument panel in billows; turns out the terminal screw had contacted the wire coming from the outside temp sensor behind the front bumper, melted through the insulation, and applied 12V to the temp sensor. Egad. The fix was to remove the fuse for the blower and install a fuse holder and a 30 amp fuse outside the big fuse box. Rather than the official Mercedes-Benz part, I bought a holder at a parts store; worked perfectly. Also periodically replace all the fuses and keep wiring terminals clean and tight. And if you are having weird electrical problems, locate, clean, and tighten the grounding points.
Another thing: clean the leaves out of the firewall well, before your car burns up! Mine had so many leaves in there that it's a wonder it had not already burned before I got it. I was cleaning it out because their presence offended me, when I learned about the resistor being in there. Also I figure they will promote rust in this area. At any rate, it's much better they are not there.

the blower in my 420sel was not working so I started troubleshooting from the fuse box .I found the fuse intact but the plastic of the fuse box at that location was melted and as the metal contact distanced itself the fuse lost contact saving the whole box and dice. I jerry rigged the connection to figure out what was going on and found within a matter of seconds the fan would run but the fuse and contacts where extremely hot(could not touch them).I then pulled the fuse and still have not resolved the high current draw. if any one has any ideas I would like to hear their opinion. The car has 200.000 km ,my aussie ford fairlane has more than 1/2 a million km and I have never seen anything like it

I believe that the blower fuse looks identical to the glowplug fuse in the 124, except one is 30a and the other is 80a, a simple mistake for a mechanic unfamiliar with this car to make and one possibility.

This might be a possible answer for this issue.
 

If you check this video you'll see at 0:46 that the blower resistor on this W126 coupe has been moved to a more sexier location. It's safe there and it'll always get hit by air from fan and no leave accumulation issues. I think that's a very good, permanent mod. Ok, just went to confirm and it turns out that all right hand W126 cars had the resistor mounted near the reservoir tank. I have posted pictures of what I could find. Turns out it isn't a mod but done by factory for RHD cars. I think I'll do that to my 1991 420 as a permanent fix. Location is perfect ! Questions do arise why the resistor is always mounted opposite the blower motor in the engine bay. RHD would have the blower motor on the left side passenger side and the resistor is mounted on the right side in engine bay. On US and Euro the opposite is true. Here is the youtube SEC 500SEC 2.5" Custom Twin Exhaust Sound and takeoff with LSD - YouTube as I mentioned what we're looking for is at 0:46. If anyone could let me know if it's feasible or a danger due to running wires which will carry serious current. With other words : Let the think-tank session commence:) Thanks

Hmm
 

That is nice.


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