Xantia 1.8i Mk2 - No Power on Fuse 21

[smc6]

Xantia 1.8i 2000 Mk2:
Heater blower has no power on red cable at brown connector into motor. I've replaced the resistor, brushes, and relay. The fan/blower works when powered separately.
I have power on fuse 5 but no power on fuse 21.
There is power on Block B in the engine fuse box.

I don't know how to proceed to figure out how to trace the fault as to why fuse 21 is not getting power.
I've reviewed the various threads hoping to find the answer.

Questions:
How do you remove the fuse block and is it worth it to look for something burned out?
What feeds fuse 21?
Can I jump some wire to put 12v into the relay and do so without messing up something else?
Any help or wiring charts would be appreciated.
Steve

[VertVega]

Recently I've also been studying the electrical diagrams of Xantia Mk2.
The answer would be in the diagram sent by CitroJim which is called mk2excachvcct.jpg
You can try to search with this name.
You'll find several links and here's one of them: Another Xantia Blower Thread - now fixed
It looks like F21 supply comes from one of the maxi fuses in the engine compartment fuse box.

[Johnny Cogs]

This sounds identical to my synergie blower issue, but someone has run a feed from fuse slot 3 to the red wire from the brown plug... with the switch unit unplugged the fan runs on its slowest speed. with the unit plugged in it just stops. Sorry for threads crashing, but my thread is a dead donkey :/