Fan Thermoswitch Temperature: "5-cylinder engines EXCEPT North America" ???

[mboucher70 at hotmail.com]

Haven't posted here in a while...but still follow the forum regularly.  Got a few days off, and thought I'd ask a few questions that have been on my mind.

I've got no real problems with my Audi.  1990 and going strong.  All of us on this forum have some degree of 'tinkeritis', at least mental tinkeritis meaning we wonder why something is how it is, and might it be better another way.  I hope that this is forgivable.  To tear it apart and make changes when its working fine sets you up for the dreaded title of 'tinkerer'...but if I tinker just in thought, not in deed...yet...I hope you won't be too harsh on me...here goes:

I noticed that it doesn't take much to get the electric fan to kick on.  As soon as  you're stuck in traffic or stop/go traffic, and the temperature has reached operating temp, it kicks on.  Withing less than a minute it usually kicks off.  And it does its job.

Looking at the specs for the cooling system, something comes to mind:  The thermostat for a 5 cylinder is set to begin opening at 87C (188F).  The electric fan is set to turn on between 88 to 93C (190 to 199F) for all 5-cylinder North American cars.  That's an awfully tight gap: the fan will start within as little as 1 degree C of the temperature that the Thermostat starts to open.  

The electric fan for all other cars (which would include 5-cylinder cars in every other part of the world) doesn't start until 93 to 98C (199 to 208F).  I'd imagine that with a setup like this, there's going to be a longer gap between the thermostat opening and the fan kicking on. 

The thermostat remains closed as the car warms up.  When it reaches 87C(188F) it begins to open.  But for everywhere outside North America, the temperature would then need to climb a minimum of 6C (11F) before the fan starts to run.  

So, on a European car, it would seem that the operating temperature would be a big higher, and the fan would run a bit less.

Thus I'm curious...why the difference?   If it was just California cars with their catalytic converters and special 'California emissions' regulations (at the time) that I'd understand it.  I'm going by the Hayes manual and and it specifies the difference for all "5-cylinder engines except North America".

Thanks for any insights

MC