Help! Fusible link melting conduit!
 

Hey guys I just put a Lincoln Mark 8 single speed fan on my K5. and since I've done that my 16 gauge fusible link has been melting the conduit on it, it hasn't been blowing the link but it has been getting so hot it's melting plastic, and I noticed also my 140amp internally regulated alternator is getting way to hot to touch.
I think I have it all wired correctly with 10 awg for power and 16 awg for trigger. I have the 70 amp relay power running straight to the positive battery post with a 50 amp breaker, the fan ground running on to the firewall ground and then I have fuel injection with built in fan control that triggers the relay ground. I can't see why it's heating up the fusible link since the power isn't wired through it. So I think the alternator must be doing it? Do I need a 14 gauge fusible link?
Any ideas would be great thanks!

Re: Help! Fusible link melting conduit!
 

I have run that fan before and had it wired pretty much like you described, straight from battery, to breaker and relay then fan. The only time I had wires melt was when It ran for about 4 hours straight in Texas heat. I ended up replacing the old noisy fan motor (mine was used) and adding a couple more ground wires and locations.
What do you have running off of the fusible link?
Does it blow when the fan first starts up? I seem to remember that fan having a high amp spike when it started.
Or does it blow after it has been running awhile?
This is a total guess but, maybe when the fan kicks on, the alternator is fully kicking in and blowing your fuse?

Re: Help! Fusible link melting conduit!
 

The link hasn't blown yet it just gets REALLY hot and melts the insulation it takes a few minutes of the fan running for it to get to that point.
The fusible link runs to a junction block that powers the stock wiring(blue), two under hood lights(yellow) and two led light pods(red).
Then on the battery post itself I have fuel injection unit with an electric fuel pump(orange) The fusible link(white) and then the fan itself(purple). I can't figure out why the fusible link would start to melt since the fan is wired on the opposite side of the link. You might have something there with the alternator doing it.. I was actually thinking what would happen if I wired the fan to the alternator itself? That way it wouldn't have to flow through all the wire to the battery? The relays are all on the driver side

Re: Help! Fusible link melting conduit!
 

The main thing is to know what the rated amp draw of the fan motor is. I looked on the internet and found a post about that fan on another site.
http://www.pirate4x4.com/forum/gener...ctric-fan.html

Re: Help! Fusible link melting conduit!
 

Just a thought.... Is the battery in good condition and holding a good charge? Wondering if it's bad or going bad and the fans are pulling power from the alternator, bypassing the battery so to speak. That would explain the wiring, fusible link and alternator getting hot. Lots of current going thru them.

Re: Help! Fusible link melting conduit!
 

I would add some more grounds especially on the fan also check your grounds from the harness to body, motor to harness, and motor to frame grounds. Grounds were never a strong point of gm those years but they also did not have much electronics.

Re: Help! Fusible link melting conduit!
 

It should be, it's maybe a five month old yellow top optima

Re: Help! Fusible link melting conduit!
 

I'll try adding more grounds all around the body.

How do I add more to the fan? It only has the pig tail?

Re: Help! Fusible link melting conduit!
 

There's more current than should be going through the things hat are getting hot. Its that simple.

Adding grounds, while possibly needed will allow for more current to flow, and you may find the fusible link then cooks.
I'd measure from the closest ground to the positive side of the fan, then direct from the battery ground to the fan + side. Poat the results.
I wouldn't run a fusible link through that ribbed tube since its going to melt if the link gets hot.
I see in the OP's pics that there are several connections to the + battery post, as well as a single post junction block. Nasty. I'd get a junction block w/ multiple possible connections from a square--they're mounted to the FW above the passenger side valve cover. Maybe mount it on the passenger a bit behind the normal location of the original JB. I'd also probably mount the relay for the fan (or maybe all of them) near the junction block on the fender.

Then start asking when is the fan running?

Re: Help! Fusible link melting conduit!
 

I assume this is a used fan. I am also assuming that this fan uses a brush style motor. Did you attempt to clean out all of the old carbon build-up and carbon dust out of the fan motor before installing it (tapping fan motor and letting carbon dust come out of case vents until no more comes out, rinsing windings with an electronics cleaning spray until it runs clear)? Excessive carbon build-up from brush wear will increase amp draw. Eventually, the carbon build-up will form a short in the fan motor, the fuse will pop, and the fan may not run again even with a new fuse until the short is cleaned out. Just a thought. I went through a similar situation with a Bosch fan motor.

Re: Help! Fusible link melting conduit!
 

I blew it out pretty good with an air compressor, and someone told me the Lincoln fans were brushless but I can't be certain about that..

Re: Help! Fusible link melting conduit!
 

Sorry about all the questions I hate to bug people

Re: Help! Fusible link melting conduit!
 

I got some more time today to measure voltage and check wires while the engine was running. I found that when I measure the voltage from the battery ground to the charge post on the back of the alternator it was 14.4.. but I only get 13.03 post to post on the battery, both while the fan and engine were running.. what's causing that big of a drop between the alternator and the battery?? Is Stock wire size a culprit here?

I also ran the cooling fan with the engine turned off and none of the wires even get warm. Does that mean this is charging related?

I didn't realize it when I installed the new harness, the Charge wire has a built in fusible link as well(it also gets hot like the other). so I guess I could delete one of them?

Re: Help! Fusible link melting conduit!
 

The only other bit of advise I got is that you should really replace that bungey cord with a proper battery hold-down:)

Re: Help! Fusible link melting conduit!
 

I looked at the post from the other forum and some other sites and they are using 14 g links. Those fans pull some high amperage. I saw that the 2 speed and variable speed versions pull over 40 amps on high and move 3000 cfm of air. Not sure what the single speed versions pull, maybe 25 amps.

Re: Help! Fusible link melting conduit!
 

I just looked at this again, I see now that you say the fan is connected straight to the battery. That should bypass the fusible link unless it needs to pull current from the alternator, when the battery runs down and the alternator starts charging it. But you also added an electric fuel pump, leds and other stuff. I would increase the size of the wiring. You need to calculate the total amperage load to match that higher amperage use and higher amp alternator.

Re: Help! Fusible link melting conduit!
 

Two wiring diagrams I looked at show a fusible link between the battery post and terminal block only and not one from the battery to the terminal block.

Re: Help! Fusible link melting conduit!
 

If the FL gets hot when the fan is on, then the red feed to the fan relay isn't powering the fan... I'll bet the wiring is off and all the fan current is going through the FL. I have a big air compressor in the garage that had the starter (big relay) and pressure switch wired so that all the 27A motor current went through one 3A contact in the P-switch. And it ran that way for many years. The point is, its not hard to get the wiring a bit off.

I'm pretty sure you aren't using a 16 FL. My understanding is one size smaller (larger number) than the load it protects, so yes, 12AWG FL for a 10AWG wire.
If the FL isn't in the run from the battery to the fan relay, the issue is something else.
I didn't make it too clear, but the voltage measurements are with the fan running.
That difference in voltage by changing where you put the meter ground says you have sketchy grounds.

Finally, what the fan is set at is no indication of what the fan is actually doing.

My aftermarket fans on my previous 2002 truck would melt 30a maxi fuses and the holder even sometimes not blowing the fuse. Tried lots of things including even swapping out with new fan motors. Ended up being a bad ground. Ran the ground directly to the pigtail on the -battery terminal and no problems after.

Same scenario on my 68 firebird after putting electric fan. I installed the correct amp circuit breakers until I could find the problem. Ended up being the Same thing with bad ground due to newly painted parts.

So that's my guess as well.


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Re: Help! Fusible link melting conduit!
 

I'll try running the fan ground straight to the negative battery post and I'm going to add extra grounds from the block to the frame to the fenders and core support

Re: Help! Fusible link melting conduit!
 

I've done grounds everywhere, and nothing changed. But the last couple hours I've been messing around with my charging system and I had a piece of 8AWG wire layin around. I disconnected the stock cable from the alternator post and ran the green wire straight from the alternator post to the positive battery post (bypassing the fusible links) and now my battery showing the same amperage as my alternator. and since my fan and fuel injection system are all wired to the positive battery post my ammeter doesn't show a load when they come on. And my stock wiring is still protected by the fusible link, and the fusible link doesn't get hot now. Is this a viable way to wire my alternator?

Re: Help! Fusible link melting conduit!
 

To answer your question yes you can do it but I would put a fuse in that wire just in case. Every vechicle I have had I have upgraded the charge wire between the alternator and battery since I have installed fuel injection on most of them. The factory charge was ok for stock applications but when you add things like you did the factory charge wire is barely large enough to carry the load that is why it was getting hot since it was carrying alot of amps but it had high resistance which makes heat. The larger wire you installed can carry the load with less resistance hence it is not getting hot. All the grounds you have installed are not wasted it helps the electronics live longer since they are getting a good ground and battery voltage.

Re: Help! Fusible link melting conduit!
 

What size fuse would be good for a 140 amp alternator?

Re: Help! Fusible link melting conduit!
 

You will need a min of 140 amp fuse. The best place to find a fuse holder would be off of a ford truck or full size ford expedition it is normally mounted right above the battery on a ford. They normally use a 140-180 amp fuse. One other is a chevy suburban between 1998-2000 with a towing package and dual battery option.

Re: Help! Fusible link melting conduit!
 

A 140 amp fuse will not provide any of the intended protection for your electrical devices. Each device should have its own properly rated fuse between itself and the power supply. It should also be noted that a charging system or battery only provides amperage that is being drawn by a device. If too much amperage is flowing through a device, it is because that device is faulty and it is drawing extra amperage to operate. Alternators and batteries do not force excessive amperage into devices, or anywhere else that isn't drawing it.