1989 Mazda RX7 Electric Fan problem

Electrical problem
1989 Mazda RX7 70k miles

Hi

Am having a bit of a problem regarding my electric fan.
Sometimes the fan stops to work recently for some unknown reason, thus my water temp goes up.

The fan usually kicks in automatically around 89 degrees.
When the fan stops working I had to pull over, switch the engine off, pop the hood up & play about with the fuse, eventually it'll come back on.

I notice when am trying to get the fan back on via playing about with the fuse, I can hear the relay clicking.

I have changed the fuse & relay thinking it should solve the problem but no. It still occurs.

Any ideas?

Regards Alex