Barry,
Yes, the AC has to do with why your fan engauges frequently, it takes heat in order to make cold. When the AC is on, the condensor will get warm, therefore the it needs to have air running through it, to cool it down.
I have electric fans on mine, and have them wired in line with the AC, so that when the AC in on, so are the fans, otherwise the engine would over heat if left idling for a period of time.
Later, Rob