2004 mustang gt cooling fan question.

Can somebody help me out with this question. When you turn the a/c on does the high speed or low speed cooling fan come on? Mine doesn't come on until the high pressure in the ac gets up to about 245 psi. Ive replaced the ccrm and the cooling fan , ive checked the fuse everything is good. I replaced the fan because the motor was loud. But I always thought when you turn the a/c on the high speed fan would run all the time am I wrong? It's a 2004 mustang gt 4.6 auto.

well I figure this issue out today. the answer yes the fan comes on. ended up at the fuse box under the hood where the battery wire off the battery connects to that fuse box some body had overtigthen or something but they broke the fuse box where the stud comes out and bent the main power part of that fuse box. so the stud connects to a metal bar that connects 12v to one side of the fuses and it was bent to where three connections were actually not being made. well the first one is the power wire that goes to the ccrm. so thats why my fans weren't coming on.