Peugeot 306 XS Engine Fan

Im having trouble with the cooling fan on a 1995 N Reg, 1.6 306 XS. (Non
Air-Con Model) Manual 5 speed.
I had a slight knock on the front end of the car, which has now been
repaired.
But the engine fan does not switch on, I have repalced the whole fan unit
with a 2nd hand unit (the casing on the old unit was bent). The fan itself
definitely works,I have tested by conencting direct to the battery.
I also believe the radiator thermostatic switch is Ok, as I have bypassed
it by bridging the connections in the connector. (This works when power is
supplied direct from the battery, but from the actual fan connecter the fan
does not operate...)
The problem seems to be no power going through to the fan via the power
connecter. I have checked the 2 fuses in the fuse box which are both OK.
Any one have any ideas ???
I was thinking relays, but I cannot locate the relays, can anyone point me
in the right direction ? I have seen relays in the fuse box but do not know
which ones are for the engine fans. Are there any other fuses/relays in the
engine compartment fuse box related to the engine fan ?? I've tried the
wiring diagrams, but im not too good at reading them.
There is one single speed fan.