auxiliary fan automatic? starting temperature

[workingonit]

At what temperature will the auxiliary fan on a 2001 X5 3.0i come on, if there is no mechanical fan, the replacement aftermarket electric puller fan is unplugged, and the HVAC is switched-off? I'm assuming that the DME has a specific temperature programmed. Or not?

I'm going to be using carb cleaner to test for vacuum leaks, and I'm wondering if the auxiliary fan can be trusted to keep the engine from overheating if I take too long a time underhood.

And I'll have some cardboard blocking the air blast from the aux fan, placed between radiator and engine, if the aux fan might come on too early, giving me added time to spray the hoses.

Meanwhile, I'll have a phone with Torque Pro app displaying coolant temperature, engine revs, and fuel trims in hand while spraying the lines, but am wondering how much leeway/safety margin I'll have if I get distracted.