I have a 05 4x4 Z71 crewcab Chevy 5.3L automatic trans. Just curious about the correct operation of the electric engine cooling fans. Are they a 2 speed fan? When I start the truck cold, the fans seem to run at a higher rpm for about 3-5 minutes. There is a lot of fan noise under the hood. Then after the 3-5 minutes the fans slow down to a slower speed. The fans will eventually shut down and cycle on and off as I turn the a/c on and off. At what temp do the fans cycle up to that higher speed? I have indicated around 240F on the temp gauge before and the fans just run at the slower speed. Are they supposed to cycle up to that 2nd speed? I have had the truck to the dealer and they dont know anything about the proper operation of the fans. It seem like they should cycle up at some point and try to save the engine from overheating. I am new to the GM Truck Club and think it is great!! If anyone has any info on this it would be great to hear from you. Thanks!!