You should be hearing the fan clutch in before you get to 100 C (the mark between 80 and 120). Try this. Start the engine from cold. Rev it a few times to about 2000 rpm. Remember what that sounds like. Let it idle until about 82-85 C. Rev it again. Should sound about the same. Now, turn on the A/C, let it idle until it approaches about 100 C. Try the rev thing again. It should start to sound off if it's working. It is a distinct turbine like roar. If you do not hear it, wait a bit longer and try again. The fan clutch usually starts to come in between 90 and 100 C. If you don't hear it at all, the clutch is worn out and will have to be replaced.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.