Hi I have a xantia 1998 diesel td 1.9 ,the air conditined works but the fan and the controls for it don't I cheked the fuses and they are fine I put a 25 amp swich liked to the fan it woked for a wile but breaks again . What can it be and what is the cheapest opton.

The fan motor may be the problem. If the fan is what is taking out the fuses, replace the fan/blower motor and retest.