I have a 2005 Vectra C with Z19DT. Recently i had to change the rads and the cooling fans due to a slight accident in the front. The fans are brand new.

Can someone tell me how do they work ? When i enable A/C , the big fan starts to spin on speed 1 i think (it's slow). The little fan is stopped. When the temp reached 96-99 C (read in the hidden menu, is it normal for diesel to go up to 100 C ? ) , i popped the hood and still the big fan was working slowly, little fan stopped, but the cooling liquid dropped down to 92-93, so it worked.

When does the second cooling fan need to function? I checked my opcom and no p1481/2/3 errors.

Is it possible if the thermal resistor on the cooling control module is gone, the fan would not function, but without an error code? Being electronically controlled, it must generate a low voltage or opencircuit error if this is the case

Thank you