Jim GM4DHJ ... wrote

Dig out the resistor pack today from the blower after hanging upside down
under the dash...seems it is the thermal fuse that has gone all the
resistances test OK and no wiring or connectors are melted....

....Thermal 216c fuse is £1.50 on ebay....do you think it will solve my
problem if I replace it? ...

Only one way to find out. They can die for no good reason
and they can fail for the good reason they are there.

and can I just short out the thermal fuse and see if all is working ? ...

Yep.

would have thought so ...