Here is what I have seen. High humidity and outside temps in the 80's, full egr delete and tunes from Elite or SCT. Cruising at a steady speed of 70 for about 25 miles and A/C on high. Wrench light comes on, 22 degree spread of eot/ect. AC off it doesnt seem to come on. Towing it comes on within 20 miles unless I turn A/C off. Put egr valve back in and NOW the engine cooling fan comes on and the wrench light seems to stay off. fyi