the fan wire is directional, if you hook them up in wrong direction, it will not break it, but it will not spin either. You think you should hook black to black and red to red but you are wrong. I have to hook my black to red in order to get it work. Also it only spins when hotend temperature is higher than 50C, so turn hot end on when you test your fan.

Make sure the fan blow winds towards the front (door)

I didn't find the exact model, but I did find one with 0.19A http://www.jameco.com/z/AD0412XB-G70-AD … 32201.html

However, even if I bought it I don't know if it would work. I tested the pins where the fan hooks up with a multimeter and there is power, but the new fans I bought still won't turn on when I plug them in. I must be doing something wrong.

I may splice into the vent fan in the back to power the hotend fan.

The way XYZ and many printer companies did their logic is that power is always at all points needing it. So if you measure from say a common ground like on the PSU or frame to the power pin at X component you will see power. The way they control those circuits is by switching ground off and on for those circuits. So what you need to do to test is to put your positive lead of your meter on the 12 volt line from the power supply then put your negative lead at the negative side of the circuit in question and see if your meter shows power then when the circuit should be on. If not then the circuit is bad.

I didn't find the exact model, but I did find one with 0.19A http://www.jameco.com/z/AD0412XB-G70-AD … 32201.html

However, even if I bought it I don't know if it would work. I tested the pins where the fan hooks up with a multimeter and there is power, but the new fans I bought still won't turn on when I plug them in. I must be doing something wrong.

I may splice into the vent fan in the back to power the hotend fan.

Sounds like you blew a fuse on the mother board!

However, even if I bought it I don't know if it would work. I tested the pins where the fan hooks up with a multimeter and there is power, but the new fans I bought still won't turn on when I plug them in. I must be doing something wrong.

I may splice into the vent fan in the back to power the hotend fan.

It is odd that even when I just hook up the stock fan to a 9V battery it wont turn on like the replacement fan will.

I might try the 80mm fan solution, but I would rather just get a 40mm that can be plugged right in.

(Jr fan has 10k rpm and pushes through good 11-12CFM if my memory serves well)
Jr has all metal hotend so insufficient cooling will cause clogs as with any other all metal hotend if not cooled properly.
Coldend aka heatsink is particularly small, nearly twice as small as regular v6 like hotend so even more airflow is needed.
Also Jr fan doesn't push the cold air onto the heating but pulls hot air away... Why do they do that?! Actually there is a reason.
Cold air intake is at the bottom and by pulling air that way it generates airflow around the printed part acting as part cooling fan.
And guess what - when you cool hot melted plastic with air it's gets warm itself so effectively intake air is already warm...
Ehh Jr... It's one particularly "interesting" machine.

Also don't reverse fan so it blows towards heatsink, if you do so you will introduce hot air part "cooling" fan and your prints will look pretty sad...
So yeah... Either you find similar fan or come up with alternative solution...

Talking about alternative solutions, I did used one particularly interesting one you might consider.
I've printed 2x adapters (kind of a funnels) 40mm to 10mm round tube and 80mm to 10mm tube, bought 10mm pvc hose and 80mm fan.
Placed 80mm fan at the back of the Jr (empty fan space at the right hand side), 40mm adapter instead of the fan and zip tied hose to both ends.
It's a bit tricky to find good placement for the hose mid air but doable.
It was quite neat solution and Jr was much more quiter, 80mm fan achieves the same airflow with ease.
As of wiring I've spliced back fan cable to accommodate another fan.

Hope this helps.

So... i was trying to clear a jam so i took off the extruder front cover, unscrewed the cooling fan, and took of the fan shroud. Stupidly, I turned on the printer, and started heating up the extruder with the fan hanging off. The cooling fan turned on and 3 of its fins snapped off. I've searched and searched on google and other websites and cannot seem to find the exact model fan. The model number is Adda DC Brushless AG04012VB107100. It is a 12V 0.18A 40x40x10mm fan. If i cant find the exact fan, is it possible to use another one with lower amps? Also, its stupid to buy an entire extruder for $100 when its just the fan that's broken

Any fan of the same dimensions and voltage will be fine. The current on a fan is low enough to be of no concern.