Ok, I am on the verge of going nuts. For the past few months I have noticed a very loud and annoying sound coming from what seems to be behind my passenger airbag and possibly my head unit. It almost sounds like some sort of fan that is way outta whack, not nessicarially a rattle but somthing of the fan type. It is not affected by my A/C unit or any air (it still happens when my air is compeltely off); when I turn off my HU it still happens; when the car is off it stops. I have noticed that it seems to be affected somewhat by my throttle and breaks... It might sound really wierd but when I am driving without any music on it seems to change pitch/volume level when I accelerate/break.

Does anyone have any idea what this god awful noise is, and how to fix it?! It's driving me nuts! HELP!!![:@]

 

By head unit... Are you referring to the HVAC control (heating, ventilation, and air conditioning)?

Does the noise change when you change fan speeds on the HVAC control? Does it change when you change the temperature on the HVAC control? How about you change the modes on the HVAC control?

It is possible that a) some debris has found its way down into the fan case and is contacting the fan cage. b)the air temp blend door has malfunctioned and continues to try to move even though it has made it to the fully open or closed position. c) one of the mode doors has failed and is causing the clicking... 'C' is a stretch as most all of the mode doors are vacuum operated. I do believe there is one mode door that is electronic, but I can't remember which one it is. I believe you have to have the automatic climate control for there to be any electronic actuators in the HVAC system though.

 

When I am referring to head unit I am stating the deck/radio in my car. I was just using it is a location refrence to where I think the noise is coming from.

It has nothing to do with anything invloved with the HVAC. Nothing with temp, speed, setting... Nothing.

The noise is not actually a clicking; jeez it is a hard one to describe. It is more of a "puffing" or a faded, soft "hissing" noise. Ok, this might sound kinda wierd but it's the best way that I can describe it. When you are at the dentist and they spray the water in your mouth then give you the suction hose/tube thing? It sounds like that with a bit of a puffing noise added to it repeditivly. I don't know if that helps at all with describing the problem but I thought I would throw it out there.

I am so lost and frustruated on what to do i've had enough with this damn rattle trap!

 

The HVAC head unit is vacuum powered. It is possible that one or more of the lines has started to leak and is causing the noise that you are experiencing. The vacuum may be strong enough to still operate all of the HVAC components even with the leak.

 

That definatly sounds like a possiblity. My HVAC system still works perfectly fine; that's the only reason I would think that is not it.

Would this be a fairly easy fix? I do not know much about tearing the dash apart in my '00 so it would have to be a fairly light project.

 

After re-reading your original post and the follow ups, it does sound like a vacuum leak inside the cab. There is one other thing that I will mention and that is the cruise and/or throttle cables resting on the PCV hose that runs between the driver's side valve cover and the intake manifold. The PCV operation could be transmitted through these cables into the passenger compartment. This noise is typically described as a stripped gear clicking noise so it may not be applicable.

You will have to remove the lower kick panel under the steering wheel (atleast remove the top screws and loosen the lower ones) to gain access to the two lower screws on the instrument trim panel. Then there are two screws (IIRC) above the main instrument cluster and from there everything else should be spring clips. just start at one corner and work your way around. Once you get this off (you may have to disconnect the power from the cig lighter), you should then be able to remove the screws for the HVAC control head and pull it out. I posted diagrams of the vac system for both the auto climate control and manual climate control some time ago. Let me see if I can dig them up.

Auto Climate Control:


Manual Climate Control:



With the diagrams, what you will want to do is start the truck with the HVAC head disconnected, then use a golf tee (or other suitable item) to plug the vacuum source on the vacuum harness. If you still hear the noise, then you have a leak in the supply line. If you do not hear the noise, then you have a leak in one of the lines to an actuator.

 

Thanks for all of the advise. I don't know if I am up to handling this on my own yet; how much would somthing like this cost at a local shop? Any idea?