Have a 2007 Chrysler Pacifica AWD 4.0L SFI SOHC 6cy equipped with the dual heat/air temperature control. Everything works fine as far as the temperature control. The problem is when driving on open highways at higher speeds (ex. 65 to 75); I get a high pitched reed vibration coming into the cabin. Sound appears to be passenger side above the cabin filter area inside the dash. Kind of like when you put a blade of grass between hands and blow. Very annoying when driving long distances.

Problem had started after the cabin filter was replaced by a local garage. Mechanic cannot find out why and state that it doesn't do it for them. It is true that the noise is not consistent. Wind has to be in certain direction and seems to be worse when driving into the wind, rather than with the wind.

I found some parts breakdowns of the ducting, but do not quite know how to access. (Do not want to set off the passenger air bag either?) Thinking a seal or some connection came apart when the service garage pulled the cabin filter.
Does anyone have a recommendation on how to inspect or repair such a problem? I have tried searching for a technical bulletin or source for such information, but no luck.
Any help or suggestions on how to inspect the HVAC

 

I thought I should mention that if driving into a cross wind the noise is worse. Then if turning and going with the wind, the noise may stop. I have pulled out the cabin filter, and replaced it at same time. Still same problem. How can I inspect the filter housing and surroundings? Do I need to pull the complete dash or is there a simpler way? Access possible around glove box area?
Any responses to this would be very much appreciated.

 

Are all your vents wide open?...When it does the sound?...
Mine does a high pitch and hiss when one or two vents are closed. If I open them all up it stops. Just a thought.

 

I just worked on my wifes PAC and noticed when I flushed out her A/C, where the ports come into the car (pass side against fire wall) there is what looks to be the intake for the HVAC system to the right of where the A/C line go into the cab. There is this small flap on it that i could see making this sound at high rates of speed where there is a lot of air movement. Maybe check that? I don't know how you would really....maybe tape it completely shut, go on highway and see if it make the sound? the best way to get to it is you have to remove the airbox (where the air filter is). Figure might give you a place to start. I did have to replace the blower motor on her car and it would make weird noises so maybe the bearings are going out in that? When I replaced hers the bearings were shot and it was wobbling around and when they first started to go it would make weird noises like there was a mice in the glove box, then when it went totally out, it soundsed more like putting cards in the spokes of your bike when you were a kid. Like I said I am not 100% but it might give you some place to start.

 

Thanks for this information! Will look for the flap which you have indicated. The flap would be within the area you indicate. Not sure what the purpose of the flap is? I did try the ventilation in different modes (ex. defrost, dash, floor, combined,etc.) but no change. Also speed of fan. Did not have any change.

 

jisake1,

This is a great place to start, have you had a chance to see if this was the culprit?
Please keep us posted when you can.

 

Help me out, I sent reply with pictures and get this response?


"Post rejected because of a score of: 32.9 Rejection set to: 30."

 

Had my wife drive today as I sat in passenger seat. Brought a 1/4" hose and put one end in my ear to act as a stethoscope. Placed other end different locations and pinpointed noise to be in lower left hand corner of windshield.
The next step will be to try and seal from outside. Possibly silicone, not sure yet for best method to reseal? Any suggestions would be appreciated.
As a side note regarding the intake flap by AC lines. No change in external noise after propping flap open.

 

After several attempts and trials and errors. I had determined the noise to be coming from the moulding clipped between the door jamb and glass on passenger side. I had tried this before, but did not find until conditions were correct. It turned out to be the rubber edge which meets the glass. Apparently when air was forced under the moulding, it would expel under the flap and create the noise. As a passenger, I was able to reach around to windshield during high speed and feel the vibration. Removed the moulding and drove again. Problem solved. I reinstalled moulding and placed a small bead of silicone along the rubber flap. After cure, test drove and no more problem.

 

jisake1,

Thanks for the update, glad to hear things were sorted out.