Radiator Fan not working

[ProggerPete]

Hi all,
Cars developed a new (I think new, only noticed it today at any rate) problem. In the stop & start bumper to bumper traffic of go home through the city today the temperature gauge went WAY up. I'm talking almost to the upper limit of the dial. The moment we got onto the ICB though the temperature started dropping again and quickly returned to normal levels.

This made me think radiator fan so I had a look once we stopped and sure enough the fan was dead still.

Checked the fuse box and the fan fuse was blown so I switched the fuse with the high beam for the head lights and turned it on. Still no fan.

I then swapped the relay for the fan with the relay for the high beam. Still no fan. I stuck the fuse back in the high-beam socket and high beam works, so my assumption is both relays are ok.

Having decided the relays were good I reached the mistaken conclusion that the fan must have a problem. To test this I hard wired the fan across the battery and away it went. Fan itself works fine.

So now I'm wondering what to check next. If the fan is fine, the fuse is fine and the relay is fine where do I look for the fault?

[FXST01]

The Computer will only allow the fan to run when the thermostat gets to a certain temperature and turn off again once the temperature has dropped.

[fitykemp]

check ur temp sensor, think it is at the back of the motor on these, not sure tho, 6 or 8?