What would cause my fans in a 2000 Jetta TDI to not run at all, but when I pull the small fuse to check it the fans turn right on?

SOURCE: 2000 Volkswagen Jetta TDI WITH NO POWER

find your local vw service center and see if they can plug their computer in to see if there are any codes on the cpu. there may be one for an intermitent for the turbo. i ran into the same problem last month and it was the turbo veins are sticky so occasionaly it lack power going up hills. it did not cause the check engine light to come on, but there was a code on the cpu when they checked it. if it happens again while you are driving, pull over, shut the car off for 10-30 secs then restart it and see if it makes a difference. when it happened to me i called my guy and thats what he had me do and it was like a new car after that.

SOURCE: 2003 VW Jetta Charging problem

problem is that the voltage regulators on the 1.8t which I am sure is the same on the TDI alternator....is that they may work fine when they are cold....but once they warm up is when they start acting up and causing problems. I assume is has to do with some resistor over heating. This is just a common problem noticed by most people over at VWvortex.com.
So you can take your alternator to get tested but if it is tested cold then well it may appear to be working ok. When in reality it is broken. Trust me...it is a cheap enough part and easy enough to fix to not just try it. Some can even change the regulator without taking the alternator out. If you have small enough hands I can see it being done.

SOURCE: VW Jetta GL 2000, AC - Heater Fan stopped

is your jetta a 1998 or 2000? the site is showing two different years. here are instructions for a 2000 jetta gl. there is a blower motor resistor in this system. there is also a fuse integral to the resistor. it's all one unit, have to replace the whole thing. here's the step by step:
1.remove the glove box (what you need to get to is behind it)
2.disconnect the electrical connector from the blower resistor
3.disconnect the heater fan electrical connector
4.remove the blower resistor
5.remove the blower motor downward
and to reinstall
1.install the blower motor
2.install the blower resistor
3.connect the electrical connector to the heater fan
4.connect the electrical connector to the blower resistor
5.install the glove box
and of course anytime you work on anything electrical you are supposed to disconnect the battery negative terminal before you start, be warned that you might lose your radio station presets when you disconnect battery
hope that helps

SOURCE: 2002 Jetta TDI radio fuse number?

The Fuse number is..... drum roll..... 42 .... And you don't even have to have a dead battery for the radio to lock up. I have owned my 2002 tdi since New... and about 4 or 5 times a year radio dies. When you remove the fuse... don't immediately put it back in.... The capacitors in the radio have not fully discharged and if you put the fuse right back in.. chances are it will stay locked. I count to 15... then put the fuse back in. Close fuse door.... Operate radio normally till next lock up.... then repeat process. So you won't forget the fuse number... write #42 in the white space of your fuse location sticker that is attached to the inside of the fuse door. Hope this helps... tried to be detailed.

SOURCE: 2002 VW Jetta 1.8T: Coolant temp began rising to

volks 2001 1.8 T wolfsburgh . overheats to dangerous levels just after 2-3 min. of driving . let it cooldown an hour , drove again same thing 2-3 min. noticed fans not working , tried to crank the heaters inside , mostly cold air come in. easy fix or not?