Gold Resistor exploded?

[MSS]

I suspect the -9 reading is due to the temperature sesor being plugged in with the battery still connected. Reconnecting the battery after making the bumper connections should sort out the reading issue.

The rest has already been covered in the above posts.

[Rick-sta]

I've had 2 fail on the 75 now and 1 failed on my ZT. they lasted about a year or so before they failed each time. It's getting a bit annoying. Each time it happened I've found a wire no longer connected on one side of the resistor and burn marks on the resistor where it's blown on one side.

Fans have always been working fine.

[spyder]

Originally Posted by T-Cut

It suggests to me that the failure is associated with the recent work around the front end of the car. I think six weeks of normal operation would indicate the fan system was OK before the bumper stripdown. Anything that impares fan rotation will short out the circuit, so there's a strong possibility that the blades were not as clear/free as they might have been.

I wonder why the 80amp fusible link in the under bonnect fuse box didn't blow first? Isn't it supposed to prevent this? I've suggested before that this fuse is too big. To support the argument, I've replaced mine with a smaller fuse. My fan is now running perfectly well with a 40amp link despite 'calculations' suggesting the startup current needs the 80amp fuse. I'd suggest the fan wiring will ignite before an 80amp fuse gives in. To me, the size of the wiring looks more like 35-40amp.

TC

I will certainly try this when I fit the replacement next week.

Originally Posted by T-Cut

From the three or four events I've read about on the forum, they were bought from both forum traders and from ebay. I recall Jules reporting a 2-3 per thousand failure rate. Any resistors imported from China are obviously not recommended.

TC

There are 8 reports on this thread alone, but how many are running out there with the coil hanging out anyway?

Originally Posted by steve-45

Are the GOLD RESISTORS that are failing been supplied via traders on the Forum or were they "ebay" specials ?

In my case it is one of each, seems one or two on this thread are the same. I would not touch the EBay ones regardless.. Assuming that the traders are not reselling fleaBay ones that is.


I do have a suspicion that my fan was running continually for a few days(on econ mode). Put it on the Test-book and it ran fine during and after the test. May have just been a stuck relay?

[Mike Trident]

Latest Update:-

I just went out and pulled off the front bumper. Yes, the fan was very free, A closer look at the resistor mmmmmm it's blown a coil wire out of the bottom and has signs of massive heat at the bottom end.

I thought, mmmm let's turn on the ignition see what happens! Can't believe it! it's actually working as it should. Fan working at low speed, everything.

Turned off ignition and and put my fingers onto the resistor, cool! so the fan is actually keeping it very cool, as it should.

So what caused it to overheat? must have been lack of fan cooling. I have eventually put it down to my own fault. I notice that the bottom of the fan runs very close to the plastic undertray panels. I believe that starting it up to check the lights without fastening the bumper on fully was my error! If the undertray was pushed up even very slightly it would stop the fan from working and would allow the massive heat build up in the resistor.

I have however, learned from the experience, Whenever I remove the front bumper. 1. don't turn on the ignition or start the engine without poking a thin stick through the grill to make sure the fan spins freely. 2. Get my wife to turn on the ignition while I look through the grill with a torch to MAKE SURE that fan is spinning. 3. Change the fuse to 40 amp, because a fuse that allows your car to nearly set on fire and not blow may as well not be there.

The resistor in my car, was not from ebay but I would suspect they are all from the same place.

Spyder:- that's scary!!!!!
T-Cut:- You were spot on!!!

[T-Cut]

Originally Posted by Mike Trident

I have however, learned from the experience - - -

3. Change the fuse to 40 amp, because a fuse that allows your car to nearly set on fire and not blow may as well not be there.

Thanks for your update.
These resistors fail, for whatever reason, now and then but the possibility that it could start a fire is clearly unacceptable and why I've previously suggested swapping out the 80amp fuse for a 40amp one. My fan has operated normally with a 40amp fuse for well over a year, so I'm reasonably convinced that the original fuse is unnecessarly big. The choice of 40amp was more or less a guess on my part. I've read most of the threads discussing the mathematics of the system and 40amps seemed a good starting point to me. I may test out even lower rated fuses until I find the minimum consistant with reliable fan operation. I'd much rather have the fan fail from a blown fuse than from a fried harness. I'd suggest everyone with a resistor type radiator fan might think about doing the same.

TC

[HarryM1BYT]

I replaced the original from new and open circuit resistor on my car when I bought it 5 years ago, with a gold 100w sourced from ebay, supposedly from a well known manufacturer. No issues at all.

I suspect the issue causing some to fail, is not them burning out or over heating, rather that they are not well enough sealed against moisture ingress. They were never designed to be installed out in the weather [1]. Moisture gets past the seal, inside the resistors rapidly get very hot, likewise - rapidly turning the the moisture to steam and blowing the seals out.

I used to use loads of these gold high wattage resistors, in large expensive control panels. The panels were installed in generally cold, high humidity environments (water treatment and pumping stations). Mounted inside the panels they provided a continuous source of warmth, to keep them dry and free from condensation. I never heard of a single one exploding.

[T-Cut]

Originally Posted by HarryM1BYT

I suspect the issue causing some to fail, is not them burning out or over heating, rather that they are not well enough sealed against moisture ingress.

It's no doubt a possibility, particularly if a detergent is present in the water to reduce its surface tension. Someone reported failure after washing the car, which illustrates the idea. I can't see rainwater penetrating inside one myself. But since there's no simple way of preventing such ingress, it has to be accepted as something that happens now and then. Jules' figure of 3 in 1000 units failing is presumably a measure of the risk involved. I reckon that's not worth legislating against. But it's worth minimising the consequences if it happens by protecting the wiring. Hence my use of a 40amp fuse.

TC

[Avulon]

Originally Posted by macafee2

I too had one fail last year. Had been on the car for about 2 - 3 years. one end had blown out. mine came from a trader here as did the replacement. could water have gotten into the resistor?

macafee2

I think it's almost a certainty.

Originally Posted by T-Cut

It's no doubt a possibility, particularly if a detergent is present in the water to reduce its surface tension. Someone reported failure after washing the car, which illustrates the idea. I can't see rainwater penetrating inside one myself. But since there's no simple way of preventing such ingress, it has to be accepted as something that happens now and then. Jules' figure of 3 in 1000 units failing is presumably a measure of the risk involved. I reckon that's not worth legislating against. But it's worth minimising the consequences if it happens by protecting the wiring. Hence my use of a 40amp fuse.

TC

None of these resistors is rated with a high enough IP rating for putting in the location that it is - where it catches all the water, without taking extra precautions to seal it up there's always a risk of rainwater getting in and causing explosive failure. Btw choose a nice hot dry day to seal it - don't do it on a cold damp day!

[T-Cut]

Originally Posted by Avulon

None of these resistors is rated with a high enough IP rating for putting in the location that it is

That's basically it.
The risk of doing so, from whatever cause, is around 0.3%. As noted, I don't think that's worth legislating against. The effort should be directed towards protecing the wiring and peripherals in the event it fails catastrophically.

What I don't understand is why moisture getting into the resistor should cause a current surge sufficient to fry the wiring and anything nearby. I'd expect it to pop and that's it.

TC

[berkshirelad]

Originally Posted by T-Cut

That's basically it.
The risk of doing so, from whatever cause, is around 0.3%. As noted, I don't think that's worth legislating against. The effort should be directed towards protecing the wiring and peripherals in the event it fails catastrophically.

What I don't understand is why moisture getting into the resistor should cause a current surge sufficient to fry the wiring and anything nearby. I'd expect it to pop and that's it.

TC

Because the water will rapidly turn to steam and the fact that steam is not a good conductor means that the resistor will be out of full contact with its heat-sink.