Between 1900-2100 rpms, I can hear what sounds like a loud humming/buzzing noise that comes and goes about every 20-30 seconds and seems to coincide with the ac compressor engaging and disengaging. I'm thinking it has something to do with the compressor because when I hear it, I can make it stop or start when I press the ac dash button on and off. Also, when I'm in the above range and accelerate, it seems to get a little loud. The ac is cooling ok, just can figure out what the noise could be. Any cooling guru's out there???????????????????????

 

That sounds a whole lot like the problem I had. A kazoo like buzz, not all the time, right at 2000 RPM, and pushing here and there on the dash seemed to change/reduce the problem.

I think it was the 3rd time at the dealership they put on the updated power steering hose, which solved the problem.

The hose in question is the upper one that runs from the power steering pump to the hydro booster, and the new style has a cylinder shaped metal weight, and a crimped on kind of metal restriction. The previous hose is just a straight run.

Here's a link to the TSB.
TSB Steering Hose

 

Jeff in TD

Thanks for the info. Will check with the dealer about getting it done. Did the dealer ever say how/why the old hose would cause the problem? Did u have to pay or was it fixed under warranty??

Thanks again.

 

The dealer didn't say why the hose caused the problem, and I suggested they try this TSB after they had tried padding the dash and messing with the steering column surround.

They did it under warranty, and it totally cured the problem.

I would presume pulses in fluid pressure from the power steering pump vibrate the hydrobooster on the firewalll and resonate things in the dash.

 

Jeff in TD

Got the TSB done on 8/11 that u mention and it cured the prob.. Thanks for the info...................

 

Cool. Glad you got it fixed.

 

both my trucks make a god awful "crunch" right after you push the AC button on a warm day. sounds like the belt even chirps for a second from the strain of the ac pump being turned on. makes me and the wife cringe every time and look at each other with fear. wonder why its so violent?