I bet the low speed aux fan operation triggered by a/c high side pressure is broken. So he gets no electric fan activation until 105C. Fits the symptoms well, as the fans switch on at 105C and off at ~100C.

Try this simple test. Idle the car in the driveway, hood up, with the a/c on. The electric fans in front of the condensor & radiator should engage at low speed within the first minute or so, and possibly cycle off and on. If not, you have a problem.

Of course, this is all predicated on the a/c working. If the a/c is dead or low on charge, then nevermind.

- JimY