Ac lights flash and ac gets warm - ideas?

Greetings.... Smart car buyers!

Just picked up a 2001 in swell shape, but with one issue (I think ).
Unless its something done to save extra gas and the logic escapes me.

The ac will not consistently remain on.When driving it will shut off and the ac on indicator light will flash.There is no pattern to when it happens.If this is normal I apologize as I did not receive an owners manual with the car.

So this is my plea, request, or begging for your understanding of the problem or any possible home remedy

Many thanks

Prio