Sitting at a stoplight when I hear a noise like "pop" from the front of the car. WIfe thought a bird had flown into the side of the car because we actually felt it in car when it popped. No bird. Almost immediately the AC went hot(86º outside). I figured a belt had broken. So I lift the hood, belt is good, AC pump clutch is not turning, turn on the AC inside car and the light comes on, but no AC clutch engagement. This monster is so far different than the Fords I drove for last 40 years that I know not where to even start. THough about putting the gauges on the AC to see if it were still charged but since I see no evidence of a leak any where I didn't.
Where do I start?

2006 R/T, hemi, 125k miles.
Also of recent at a steady throttle it has been surging a bit and fuel mileage has fallen about 3mpg, could that be EGR valve?

 

Appears as though the low speed cooling fan is locked up, suppose that is what we heard "pop"?