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Dave WM

correct glass fuse size for 280z?

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while replacing my blower fan fuse I noticed the replacements were too long, my guess is its a metric vs standard thing. I have 1/4 x 1 1/4 cooper busman fuses that only have about 1/2 the contact patch it seems like it should.

so any idea of a correct way of getting a fuse?

http://www.littelfuse.com/~/media/automotive/datasheets/fuses/automotive-aftermarket/glass-fuses/littelfuse_aftermarket_glass.pdf

 

agx or sfe?

 

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It's not SFE because those are variable length depending on the amperage rating. And the AGX doesn't seem to have all the values we need.

I thought I used the ubiquitous AGC style. Those are the ones that you're finding are too long?

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yes but a just remeasured its only about 2mm too long total, maybe a true 30mm would be perfect.

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not a lot and prob not the reason for the extreme over heating taking place at the junction of the fuse to the clip. I went back and burnished it with some 500 grit to get as clean as possible, perhaps its plated and all I did was make it worse.

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I'll take a look at my fuses next time I've got the car out of the garage, but I'm pretty sure I used AGC everywhere.

As for the heat... There's no way your fuse clip should be getting hot. Have you loosened the whole fuse block off the side panel and peeked around the back side? Maybe the connection where the wire is crimped into the clip is failing? There's no way you should be getting any significant power dissipation in the fuse block. If you are, it's a problem and you need to find it before you burn something up.  

You said this is for the blower motor? On full speed? What does the motor draw? Have you measured it? I remember you had a thread about such things, but I don't remember the details.

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pulled the fuse block off examined the back, nice and clean, no issues there.

I have to figure out a way to get a direct reading of the amp draw, my meter only goes to 10 amps. It only gets hot at full power, Maybe its the blower motor. I will prob see about getting a 20 amp meter this weekend at sky junk (local surplus place), and rig up a test fuse (blown center with heavy gauge wire leads soldered to it connected to the meter) and see what I am drawing. It has already melted the fuse box cover right over the fuse. I guess I could use a shunt but I don't know how to calculate the resistance, and cant really read it directly with such low ohms that I would like to use. Maybe just use some solid copper wire of a known gauge and look up the resistance? wire is straight thru a blown fuse for the shunt?

I would not be adverse to just replace the motor with a new one, and maybe while I have it out try blowing compressed air back thru the evap with a vacuum sucking at the fan duct. The idea being to clear the evap of any blockage of the fins from years of dust and general yuck.

 

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I'm sure you could find a cool low value resistor at Sky-Junk to use as a shunt. Or an old surplus military grade panel mount ammeter with a 100A scale.   :geek:

Another option would be to use two of those cheapie Harbor Freight VOMs in parallel on the 10A scale. Based on the assumption that the internal shunts of the two meters are close enough to the same value, this should work and two of them in parallel should share the current.  I've done it with good success.

But the bottom line is there's no way you should be generating enough heat there to melt your fuse box lid. Is the melty at one end of the fuse, or over the whole thing?

 

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well put it all back together so far not getting hot. As insurance for a tight connection I used some tiny o rings to aid with the clamping force, just hooked them around the term connectors.

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got a little panel meter off ebay, 12amps at the battery with fan on (and compressor clutch engaged) will go up with alternator running. I will have to get a fuse only reading with engine on and idle up for max voltage to find out for sure how much amperage, but I suspect it will not be excessive. Not sure if the compressor runs thru fuse. But 12amps seems a bit high for a 20amp rated fuse with lower voltage from non running car. I thought fuses were generally rated at 2x the nominal current in a circuit, esp one with a high start up current like a motor or clutch?

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On 6/29/2018 at 8:43 AM, Dave WM said:

while replacing my blower fan fuse I noticed the replacements were too long, my guess is its a metric vs standard thing. I have 1/4 x 1 1/4 cooper busman fuses that only have about 1/2 the contact patch it seems like it should.

so any idea of a correct way of getting a fuse?

http://www.littelfuse.com/~/media/automotive/datasheets/fuses/automotive-aftermarket/glass-fuses/littelfuse_aftermarket_glass.pdf

 

agx or sfe?

 

I find it cool to know that a thing such as the "Society of Fuse Engineers" exists. I wonder how I can join...

"Glass fuses designed to specifications set by the Society of Fuse Engineers. All are 1/4 inch in diameter, but vary in length according to.."

 

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