They are fixed with something like this.
https://www.springmasters.com/push-on-fasteners/
You may just be able to tap them on a bit, they don’t usually come off easy.
J
On the head on newer engines , there is an overheat switch that comes on about 110 degrees n brings on the aircon fans usually a bit 2 late Anyway if that could be changed to one about 100c it would save a lot of fafing about...