Having now worked out why my coolant temp was fluctuating so much, it appears the retaining screw that holds the blades onto the left motor has done a runner, hence the blades have now fallen off (but are thankfully trapped between the grill/bumper and motor). Must have been off for a week or two by now!
Do any of the citroen gurus, or anyone else out there know what size the retaining screw is?
(I won't have time to dismantle it until the w/e to look at the other, and it doesn't look like the easiest job to remove the assembly in restricted space with grill removed)
Hopefully it isn't just the head of the screw that is missing, the rest still in situ
The second fan appears to be working properly so the temp is kept to reasonable levels at the moment, but with the air-con on and working the engine hard, the temp does rise quite rapidly (but still won't hit 90 in normal driving).
Any help appreciated,
Chris