[Vetteman61]

I may be using incorrect terminology. I have always called an inline, glass fuse a "fusible link."

If I have 10 gauge wire, would I use a 10 gauge inline fuse with a 30a fuse?

[lust4speed]

Originally Posted by gtofreek

This is 2 wire gauge sizes smaller, since there is no 11 or 13 gauge wire.

Picky, picky, picky. So I should have said four gauge sizes smaller...

Least we confuse the issue, the proper fusible link size for 10 gauge wire is 14 gauge fusible link however we get there. Problem would be the same for protecting a 12 gauge wire since there is no 13 or 15 sized wire. The count would still be 12+4=16 for the fusible link.

Think the thing is that the gauge size exists whether or not they choose to produce that size.

[gtofreek]

Originally Posted by Vetteman61

I may be using incorrect terminology. I have always called an inline, glass fuse a "fusible link."

If I have 10 gauge wire, would I use a 10 gauge inline fuse with a 30a fuse?

An inline fuse is NOT the same as a fusible link. A fusible link is a piece of wire that has a lower melting point than regular copper wire. It can take momentary overloads without burning, but any direct shorts will cause it to burn before your wiring burns up.

A fuse will blow once you exceed it's rated amperage.

[Ben M.]

Originally Posted by Vetteman61

I may be using incorrect terminology. I have always called an inline, glass fuse a "fusible link."

Yes, incorrect. A fusible link is a small section of wire designed to melt and protect the remaining wiring. An inline fuse is a glass or plastic fuse assembly that will also melt to protect the wiring (and be replaceable). A circuit breaker is the same thing only it doesn't melt (you hope) but merely opens when current exceeds a threshold - most automotive type circuit breakers are thermal self-resetting ones. You're talking about an inline fuse.

[gtofreek]

Sorry Mick, I thought you were contradicting what I said when I said two wire gauges smaller than the wire it feeds.

[Vetteman61]

So just to make sure, a 10 gauge wire definitely needs an inline fuse (if you're using an inline fuse) with a 10 gauge wire as well, correct?

[gtofreek]

Yes.

[Vetteman61]

I installed a new 30a in line fuse with 10 gauge wire as well as new 10 gauge wire from the alternator back to the first pigtail. It used to take a while for the fuse holder to melt. This time it melted after only a little use of the A/C.

Next I suppose I'll test the ground wire from the blower motor. This is very frustrating.

[gtofreek]

If they are glass fuses you are using, you need to toss it and install an ATC type fuse holder or a fusible link.

[Ben M.]

You have a current draw problem somewhere in the system. Pure & simple.

[Vetteman61]

I'm going to start by checking the ground wire that comes off the blower motor. I want to make sure it's getting the best ground it can.

From that point I'll move on trying to check things from the recommendations in this thread. I'm not exactly sure what the ohms should read if I disconnect the alternator wire and check right at the blower motor connection.

[1969CustomS]

Did you ever figure out what was causing the wire to melt? I have a 69 that is doing the same thing. I’m completely stumped

[Vetteman61]

Yes. I talked to a mechanic that worked at a Pontiac dealership when these were new. He said this was a common issue and that back then they would put two inline fuses in a row. The better solution for today is to solder in a blade fuse holder rather than the glass fuse type that came in it originally.

[Greg Reid]

I'm assuming he meant two fuses in parallel... meaning side by side to divide the current so that each one will only see half the total.
Still, I'm not sure how that will keep the wire from burning up. Once those parallel fuses are joined back into a single wire that single wire is still going to carry all the current in the circuit.

[Vetteman61]

It's been quite a few years ago, but from what I remember it was due to the fact that the old glass fuses didn't make great contact and had a tendency to get hot and melt the plastic (or possibly bakelite) surrounding. I installed the fuse holder below and it never happened again. My owned a '71 Catalina since '74, and it has never had this issue.

[Greg Reid]

Cool.. good info.

[hgerhardt]

Originally Posted by Vetteman61

It's been quite a few years ago, but from what I remember it was due to the fact that the old glass fuses didn't make great contact and had a tendency to get hot and melt the plastic (or possibly bakelite) surrounding. I installed the fuse holder below and it never happened again. My owned a '71 Catalina since '74, and it has never had this issue.

x2 for that type of fuseholder. I did that for my '66 GTO about 30 years ago.
These fuseholders were used in GM cars from the '80's and are available as a GM-Packard replacement part: https://www.bmotorsports.com/shop/pr...roducts_id/959

[Bill Hanlon]

First, the following suggestions are based on general knowledge as I do not have a '69 Tempest Custom S wiring diagram to look at.

That in line fuse usually just supplies power for the fan in high speed. There shouldn't be any other devices on that wire downstream from the fuse.

Is the fuse "melting" or "blowing"? Blowing usually results in blackish residue inside the glass tube while melting does not, but often shows a "sag" in the internal fuse wire. A sagging fuse failure can occur when the fuse is operating near its rated amperage for a long time OR when it gets hot from an outside source such as a poor connection from the fuse to the fuse holder or a very nearby wiring connection.

If you have a voltmeter, try this.

Find a couple of straight pins. Push one through insulation and into the wire that feeds the fuse upstream (towards the alternator or battery) about 6" from the fuse. Push the other pin into the wire 6" downstream (towards the fan) from the fuse.

Start the car, leaving the A/C off.

Measure the voltage between the pins. It should be zero. Turn on the A/C with the fan on low, then medium. Both should still measure zero. Turn on all electric stuff you can think of EXCEPT the high fan speed. Voltage should still measure zero.

Now turn all that stuff off and turn the A/C fan on high. I wouldn't expect the measurement to read more than 0.010 or 0.20 volts. If it is more either the fuse is defective (too much resistance) or the fuse holder has too much resistance generating heat, which causes the internal fuse wire to sag and eventually break.