Loud Noise

I Bought a 2000 Ford explorer this past November and I noticed in cold weather that there is something that turns on in the motor area that sounds like a loud vacuum cleaner and runs for about a minute and shuts off. when it shuts off it drops my tac and my truck stutters a bit.I havent noticed it in warmer weather but we havent had a lot of warm weather since I got the truck. Anyone know what this is???

Hello, don't worry about the vacuum cleaner noise; its normal. It only happens in cold weather because the computer is trying to get the engine warmed up faster, so it revs it up to 1100 rpms for a minute. The HVAC (ventilation system) also circulates warm air around the engine and thats another reason why you hear the vacuum cleaner noise.

THanks for the info Nand12