So I plan on doing the fan test after work today but wanted your guy's opinion on it. I know our trucks have that 'roar' before the engine warms up, but I've noticed while I'm in parking lots and I'm going about 10 to 15 mph, I'll get that roar. This is usually after the truck is up to operating temp and I've found the only way to get it to go away is to turn the AC off. It also happened yesterday while I was coming home from work was going about 35 to 40 mph, but eventually it went away and I think it was due to having to get it up to speed really quickly to get around an idiot who wouldn't match merging speed. Any insight would be great.