At about 100C the mechanical fan clutch should tighten and you will hear "fan roar" at 2000 revs and above. As stated, the electric will engage at high speed at about 105C. You should be able to test by letting the engine idle for five to ten minutes in moderate temperatures. Once the electric engages the temp should drop rapidly to its cutoff at about 100C.

The electric will also engage at low speed based on A/C system requirements via a pressure swtich.

In cool to moderate temperatures 80-90C when cruising at steady speed is normal, but it will go up in traffic, and the fans should engage as outlined above to keep the engine from overheating.

Duke