a/c switch stopped working

I'm old but new to this forum. I have had 1979 280 zx for 15 yrs. It has 55k on it. Problems have all been with the electrical area of the car. I had the a/c converted to r134 a couple of years back. I had to replace the a/c relay at that time and I think it needs another already.  I turned the switch on and neither the fan  nor a/c worked. Could there me another cause? If I'm right does anyone know where I could buy them. i had a hard time finding them before.

Thanks for any help. Hope to be visiting this forum often.