Mine did this a few months ago and last week. The fuse is OK, the contacts in the fuse box were dirty and semi-melted into the holder. Cleaning them with some #6 and a brush fixed it. The first time the fuse itself was a little warped so I changed it. Looking closely at it revealed a gap that opened up when the plastic got hot. I run the fan on high a lot here to cool the car down and it must be drawing too much current over a long period of time. Now that the cycle switch is fixed, the car cools down 3 times faster. Probably all of yours are bad but it takes a failure to finally notice it. The compressor wasn't running as long as it should.
When the vacuum is disconnected from the motor control (heater/AC selector) you will notice the vent doors will not open and shut when you turn the knob. When the power is off (blown fuse or in my case, poor contact) the vacuum motors will work but the cab blower will not come on nor will the radiator/condensor fan kick in.
