GMC Repair: fan clutch noise, mazda bongo, fan clutch

Question
Mazda Bongo 1998 truck (Motorhome), diesel 2200lt.  Originally when travelling a loud roaring fan like noise occasionally occurred spasmodically. 12 months ago it began to come on continuously on startup, I had to drive it for 20 mins then turn off then turn on the engine a couple of times rapidly and it would then after a few seconds turn off the roaring sound and resume its normal operation ie: coming on and off occasionally. Now I hear a loud fan noise all the time from startup and it will not cease.  I am no mechanic, I have had a look at the engine, I rotated the main radiator fan, it rotated back and forth with a bit of a push (would not spin) certainly not free wheeling, it was not slack and no lateral movement. I could not prevent the fan from rotating when using the rotation of the starter motor (engine immobilized and due care taken). So my question is has my fan clutch jambed/locked. Most of your diagnosis is for a free wheeling fan or one that does not come on at all, can these fans become faulty by being permanently on.??  Maybe the radiator fan is operating correctly and the normally sporadic roaring fan noise on hot days or long travel is something else?? If so what else could it be?? Your assistance in this matter would be much appreciated.

Answer
Hi
Just using basic knowledge of fan clutch operations, it does indeed sound as if the fan clutch is on at all times. It should have resistance or harder to turn when cold, and as the temp warms, it should loosen up, there by rotating almost at smae speed as engine.
If per chance yours is an elctro-viscous clutch (uses electrical current to change viscous material) it should then be checked by a mechanic, making sure the electrical components are operating as designed.
I hope this helps
Good Luck
God Bless
Pawl