Volvo Repair: power windows not working and AC blows only hot air, mass air sensor, amp fuse

Question
I obtained a 1990 240 dl Sedan about a month and a half ago, and the previous owner informed me that he had replaced the mass air sensor just before selling. Hoses seem to be in good shape, but I don't recall if ever the ac blew cold. I notice that my windows are able to roll down when the AC was not turned on. However, about 5 days ago I turned it on to defog my front window and now it is always on, and hot. I turned the knob from max to 0, and made sure that all buttons were off. Could I have turned on a switch on the dash and just be confused with where to turn it off?
I also have replaced the 8 amp fuse for the power windows multiple times. It seems like everyday it is busted. I switched to copper fuses, replaced all old ones, even put a 16 amp fuse in the power window slot. It always seems to blow.
could these two problems be related?
Alex

Answer
Alex, the compressor is on the same circuit as the Power windows I believe.  Whats happening is the clutch is drawing too much amperage and is blowing the fuse.  Its cheaper to replace the whole compressor than just the clutch.  Sorry for the bad news.  Roger