shop vac under hood

[BAWhite]

I have an 05, 3500. I live in east of Albuquerque at 7000 feet. Driving back and forth to work and home with the AC on there will be a sound that comes and goes that sounds like a shop-vac being turned on and off. The truck runs good and all the guages are in the normal range. I was thinking that it was the AC compressor. Any thoughts?

 

[Spooled-up]

Sounds like the engine fan cycling on and off. I believe it works off of underhood temp. Once it reaches a certain temp, it engages the fan, it runs for a while, and then shuts off. Sometimes mine will run for 5-15 seconds and then shut off.

 

[BAWhite]

do they all sound like a shop-vac ir is it just mine?

 

[CHolman]

Yes, it's the clutch fan, like Spooled-up said. Once the engine reaches a certian temp, the clutch fan will engauge and well your shop vac is on. Vechical's clutch fans come on automaticlly when you turn on the A/C and the Compressor kicks on. It has a big fan, so it's not going to be quite.

 

[BAWhite]

Thank you, then my truck is still operating perfectly since I bought it last october. Its great to have a place to come to for reliable information.

 

[ChrisKringle]

My '03 sounded like a shop vac, but my 04. 5 does not. Took it to the dealer and told them the fan wasn't engaging.



Turns out it is engaging, so do I have a weak or worn clutch?



Anyone?

 

[rholcom2]

I just purchased an '03 auto. And it seems that the fan clutch locks up EVERY time the engine comes down to an idle. Then stays locked (its hard to explain how long, but I will try) through the 3rd shift at least. I have a '98 now, and it seems it never locks. I realize this '03 is a totally different animal than my '98. But, it seems that it locks up way too long. Any advise, or is this normal? Thanks

 

[Jengle]

04 here, and mine seems to be more temp related than just on when a/c is on. I have heard it cycle off when the a/c is on, but temps lower. Sitting in rush hour at 95+ I am cleaning the engine bay, or so it sounds. Yours sounds normal to me. Now, if it stays on all the time, I would get it checked.