a) there is anything that can go wrong with the fan electrical system that would cause this, or
b) a previous owner (joker) just bypassed the thermostat control system for the fans?
I prefer to check a) first.
The other issue that might be linked to this is the Bongo does not start well. Could it be voltage drop when glowplugs need it most caused by the fans? The glowplugs are not very old and all glow red when removed and tested. Cannot see any shorting out. Linkage on pump moves when ignition switched on, but strangely drops back as glow plug light goes out, but before starting.
As you can see, I'm having a bit of fun but it is a good way of learning about Bongos.

Anybody got any experience or ideas on this? They would much appreciated.
John
Bognor Regis