1994 Cavalier 2.4l, why does the cooling fan what until coolant is too high to kick in. Idling in summer causes boil over, fan will come on, only too late.
New thermostat, new coolant temp sensor, fan, relays work, new ecm.
Only way to prevent this is with A/C on.
Seems like all components work as they should, just the fan waits to long to kick in.

 

The fan on & off temp settings are configurable in the ECM program.