MY 02 ford focus has a really strange problem, here are the symptoms

The 2 radiator fans are coming on very frequently, a lot more than normal.
The Heater/blower fan only works on No. 4 setting (ie no fan on pos 1,2 or 3)
The aircon compressor kicks in and the button light comes on but still no heater/blower until position 4, and then the aircon light goes out.

Can anyone shed any light on the problem, or suggest what to look for, i have checked as many fuses as i can and theyre ok,
I do know from the manual that the 2nd rad fan has somthing to do with the aircon!!!!

ANY HELP WOULD BE MOST APPRECIATED