Temp change with AC

[MustangGuy67]

2016 Eco Boost Premium w/pp
Cruise highway speed, 75 mph, without AC on and temp runs around 210 F.
Same speed with AC on runs around 190 F.
What causes this situation?
Trying to nail down a couple issues, temp fluctuating and over boost issue.
Could a faulty waste gate/turbo cause fluctuation in temp or a faulty thermostat?

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[Buldawg76]

The only difference between AC on and off is with it on the cooling fans are running all the time versus only when needed with the AC off to keep engine temps down. Driving at highway speeds with AC off the cooling fans will never turn on until you come to a stop and engine temp reaches 213-215 degrees causing them to turn on until temp drops below 203-204 degrees.

If you have active grill shutters they are also mostly closed at highway speeds to improve the aero of the car for improved MPGs.

BD