AC Clutch question

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Have 92 Linoln TC with 4.6

When I first start the car A/C compressor comes on and works fine.
After about 15 minutes it starts to blown warm like the compressor has stopped.

Yesterday on the freeway it ran for over an hour.

When the clutch was not engaging i looked and saw it turn a tiny bit but not engage and turn. It creeped a little bit.

My question is as the pressure in the system gets higher does the clutch have to work harder to stay engaged or does it simply engage them like a starter bendix? Also could dirt and rust get on whatever is pulled by the electromagnet and cause it not to work right. Any adjustments?

If anyone can fill me in on the way the clutch operates I sure would appreciate it. Thanks and Good Luck