Over Heating

Took the old girl. 130,000 miles on her, up to Sant a Pod on Saturday and noticed that if driven over 70.....well 80+ the tempersture started to rise.
As it was thr first warm day of the year I also put on the AC....she the really started to rise so shut that of and opened the windows.
Now just driving around in London with AC on she is rising as well.
Back flushed rad etc. but no change.
So I guess coulkd be rad or another thought is viscous fan?
How can you tell if viscous fan is working?
All suggestions as to cause and cure appreciated.

turn engine on, lift bonnet and remove the cowl, put hand in.

if you hear a thud then 5 splats then the fan is working!

you can also take a wooden shaft of hammer etc and place on the fan outer to slow it to a stop, you should find it quite hard to stop. it should then pick back up when you release!

Thanks
Thing I'll try the wood approach

try the finger test first!!!!

OK but might put on some welding gloves.
I guess my thread on air suspension problem is too dull.
Any thoughts yourself?

i dont think its that bad as threads go!!