engine roars

Just moved to Phoenix and after driving for awhile it sounds like the engine is accelerating at extremely high rpms, but actually is not. I'm just accelerating like normal below 2000 rmp's. Is this because of the heat, and if so is there something I can do to fix it?

Thanks.

What do you have, what mileage, what modifications, and what besides moving have you done to your truck recently?

2000 Chevy Z-71. 5.3L. Haven't done anything. Everything is factory with no modifications. 40,000 miles.

this is the engine fan. in colder climates you only hear them at start up. in hotter climates the clutch fan engages making it sound like the egine is roaring. also in warmer climates if you are running the ac all the time , this will also engage the fan.

Yep, at times it sounds like someone's running a shop vac under my hood. Guess my truck sucks... HAHAHHA!