The little light on the button on the dash didn't light up at all.
AND the courtesy light in the front stopped working.
AND the cigar lighter sockets stopped working.
hhmmmmmm. A fuse ? Maybe, but which one ?
Anyway today it's like really hot and stuff, so I went to the car fuse shop and stared at the handbook and guessed which one it would be and bought some - 3.29€ for eight, I think, and then came home and tried to work out how to get at the fuses and eventually found out how and got out the relevant fuse and yes, it had blown.
A new fuse inserted, the air con light comes on.
Pat and the kids will be very pleased.