Have a 02 Xterra SE S/C with 60k miles. No Aux. fan. I'm seeing the temperature skyrocket on Idle, but cool down to normal while cruising.

The A/C also goes warm on Idle when the temp increases.

The fan is belt driven and turning on Idle, but I can't tell how fast. I'm thinking the fan clutch is not engaging at is supposed? Could it be the cooling system obstruction also?

Any ideas?