How much amperage can an alternator support? no really...

[Louis-Alain Richard]

As for the response stating that the temp 
switch isn't meant to carry a high current load over an extended period, 
I think that's bull.  The switch operates the fan relay(s) and doesn't 
carry all that much current.  I use them in air cooled applications to 
operate oil cooler fans, and they run for hours under high heat 
situations all the time.  Back in the days of the 100LS, Fox, and early 
Rabbit/Jettas, we saw quite a few fan switch failures, and sold a lot of 
them.  I doubt I sell 2 a year now, except for the ones we install when 
we change the radiator.  Not much of a failure point.  In fact, I 
probably sell more fans than switches. 

John

Well John, on my car, purchased in 2001, I am on my 4th switch, OEM and
Wahler. Sometimes, after a lapping session, or stop-and-go traffic, the fan
would stay ON forever, even when the rad is cooled. I have to disconnect the
battery via the big red safety switch (custom install) to stop the fan and
make the switch cool. After that, it works normally. But the car is a 1983
Quattro, with the Rabbit ceramic fuse box, and the fan is not relayed from
factory. I guess that the 4000 is not either, even with the newer
plastic-fuse fusebox.

Louis-Alain