I have searched the forum numerous times, and the only info on this topic does not concern what seems to be my issue.

At first i thought it would be my blower motor bearings.....I get a constant whistle noise coming from the passenger floor under dash area when I turn on the blower, be it heat or cool. The faster the speed of the blower motor, the higher and quicker the pitch of the whistle.

I removed the cover, under the glove box, and removed the blower motor for inspection. When I fire up the blower in my hand, out of its HVAC ABS Duct tomb, it operates perfect, no noises. When I reinstall it into the duct it belongs in, as a thought, I added a rubber gasket where the blower motor bracket meets the duct housing thinking it was a small air leak in this area) and fire it up again, there goes the whistle again. No change. I looked for leaves when open, all clear.

I then pushed straight up on the bottom of the duct while the motor is whistling and if pushing hard enough, the duct flexes to where it must make a better seal whereever it has another connection under the dash, as the whistle will all but disappear.

Does anyone have any experience tackling this annoying problem by chance?

Any help would be greatly appreciated.


I have a 2004.5 LLY with manual dual climate zone?


Cheers,

I then pushed straight up on the bottom of the duct while the motor is whistling and if pushing hard enough, the duct flexes to where it must make a better seal whereever it has another connection under the dash, as the whistle will all but disappear.


This is a new one for me. Easy first, check to make sure the passenger vents are open. I know when the wife closes her vents off, all kinds of air rushing noises happen through the other vents.

If it's a seal problem at the blower, then you may need to find something spongy to fill in the gaps down there. There could be an inperfection in the blower case or something like that, but you should of heard this a long while back when the truck was new.

Thanks for the heads up on closed vents, I have to check that.

The truck has 40K miles and is new to me, so I do not know about this particular problem and its history.

I just know it drives me nuts.

I wonder if I remove the glove box if I can get to the seal at the top of that big black ABS Duct box that the motor is found in the bottom of. It could need tightening here? Maybe it is here the seal needs "sealing" as when I push up on the whole unit from underneath, it gets goes away, if I press up on the motor only, noise continues, so that leads me to believe it is the top seal under the windshield, behind the dash, passenger compartment.

Ditto on the closed vents. My truck makes all sorts of noise when even one vent is closed if the fan is on high. It'll deafen you in my wife's HHR under the same conditions.

I assume this is gonna get moved... ?

Sorry,


I always opt for the year of vehicle for all discussions by habit, not realizing this is engine specific.

Well, I checked this morning, oped all vents, played around with all settings, floor, defrost, recirculate, etc, still the whistle sound, increases its intensity, the quicker the blower motor speed.

I must have some duct points that need sealing behind, under the dash, is there any access if you remove the glovebox to see if there is the issue behind it?

Anyone with similar issues and a fix by chance?

Cheers for any tips......

I am thinking this TSB repair guide below for cold air on passenger side of 03 or older trucks may be my fix for my 04.5 whistle.......of my blower motor, bad seals in the cowl, hvac box seal to firewall?



Passenger SIde of Vehicle Colder/Warmer Than Drivers SIde (Repair HVAC Case to Cowl Seal) #01-01-37-008 - (Mar 29, 2001)
Passenger Side of Vehicle Colder/Warmer Than Driver's Side (Repair HVAC Case to Cowl Seal)
1999-2001 Chevrolet and GMC C/K Pickup (Silverado, Sierra) and Utility (Suburban, Tahoe, Yukon, Yukon XL) Models

2002 Cadillac Escalade

Condition
Some customers may comment that the passenger side of the vehicle may be:

Colder than the driver's side when the heat mode is on.
Warmer than the driver's side when the air conditioning (A/C) mode is on.
There may be dampness on the vehicle dash assembly when the A/C mode is on.
Cause
Condition may be due to poor sealing of the HVAC air inlet case to the front of dash or the recirculation mode door actuator may not hold the recirculation door closed while driving.

Correction
Replace the recirculation door actuator (if necessary) and repair the HVAC case to cowl seal using the following procedures:

Place the A/C control in the manual heat mode.
Remove the fixed mast radio antenna.
Open the hood and install fender covers.
Remove both wiper arm assemblies using the following procedure:
Disconnect the washer solvent hose from the air inlet grille panel nozzle.
Remove the cover from the wiper arm retainer. Remove the retainer.
Important: Use a battery terminal puller in order to remove the wiper arm.


Rock the wiper arm back and forth in order to loosen the arm from the drive shaft. Remove the wiper arm.
Lower the hood.
Remove the air inlet grille panel using the following procedure:
On each end of the air inlet grille panel is a rubber flap for the hood hinge cutout. Lift this flap and remove the air inlet grille panel attaching screw.
Remove the air inlet grille panel center top push pin.
Remove the clips that position the forward edge of the grille panel to the top of the cowl.
Disconnect the windshield washer supply hose from the bottom of the grille panel.
Remove the air inlet grille panel by sliding the panel rearward up the windshield and out.
Just to the left of the right hood hinge, on the horizontal surface of the cowl, locate a cover that is sealed in place. The cover has TRW stamped into it.
With a sharp knife, cut out the panel following the panel impression in the sealer tape.
Place a lifting device between the cover and the dash. Lift the cover enough to allow another tool to depress and release the front retaining tabs by pushing rearward on them. Remove the cover.
Look through the opening where you just removed the cover. You will see what looks like a piece of foam about 76 x 127 mm (3 x 5 in). This is the A/C recirculation door that is within the HVAC module.
Reach into the opening and carefully pull on the air inlet recirculation door. If the recirculation door moves with very little effort, replace the air inlet (recirculation) door actuator (Manual systems only). For systems with the Automatic Temperature control, initialize the system using published Service procedures.
Between the top of the HVAC air inlet module (appears as a 6 mm (1/4 inch) black strip) and the cowl sheet metal is a foam seal. This foam seal may be improperly positioned or damaged in some way (insufficient crush/sealing). This may allow outside ambient air to enter the passenger compartment incorrectly (under driving conditions). This can be corrected using the following procedure:
Important: It is imperative that a good seal be achieved over the entire surface areas (no voids or skips), especially around the rear and sides of the HVAC case to cowl areas.


Seal the area between the cowl and HVAC case with RTV Silicone Rubber Sealant, P/N 12345739 (in Canada, use P/N 10953541).
Using your finger, from the engine side of the cowl, ensure that the foam is stuck nicely to the HVAC module and does not have any distortions.
From the engine side of the cowl, working through the opening in the horizontal surface of the cowl, place a shop cloth into the opening and cover the blower fan. This keeps silicone from dripping onto the motor and causing an imbalance condition.
From the engine side of the cowl, working through the opening in the horizontal surface of the cowl, apply the RTV silicone to bridge the gap and cover the foam between the cowl sheet metal and the HVAC module case. Inspect your work with a light and a mirror. Ensure that no gaps or skips are present in the RTV seal.
Inspect your work for potential drips, runs, etc. If no problem is seen, remove the shop cloth covering the blower motor.
Apply a 3 mm (1/8 in) bead of weatherstrip adhesive, P/N 12345097 (in Canada, use P/N 10953479) around the opening in the horizontal surface of the cowl, where the cover fits into the cowl.
Place the cover on the workbench, top on the surface, and apply a 3 mm (1/8 in) bead of weatherstrip adhesive on the edge of the cover.
Place the cover into the cowl opening and snap into place.
Apply another bead of weatherstrip adhesive around the joint between the cover and the top of the cowl. Smooth this bead into a smooth surface with a finger or tool of some kind.
Place the leaf screen to the cowl. Attach the washer supply hose to the bottom of the air inlet grille panel. Do not place the fasteners in at this time.
Install the radio fixed mast antenna. Tighten 1/4 turn after contact is made with the base.
Lower but do not close the hood.
Center the opening in the air inlet grille panel around the antenna mast and then install the air inlet grille panel retaining screws.

Tighten
Tighten the screws to 2 N·m (18 lb in).

Raise the hood.
Reinstall the air inlet grille panel center retainer and front edge retaining clips.
Cycle the wipers to ensure the wiper system is in the parked position.
Important: Inspect the windshield lower edge on each side. About 51-76 mm (2-3 in) from the bottom, you will find a 13 mm (1/2 in) long black mark embedded in the glass. The black line is the position for the wiper blade to be in when the wiper system is in the parked position.


Install the wiper arm assemblies. Position the wiper blades just below the black marks in the windshield.
Install the retaining nuts.

Tighten
Tighten the retainers to 25 N·m (18 lb ft).

Reconnect the washer hoses.
Remove the fender covers.
Close the hood.
Parts Information
Part Number
Description

12345097

(In Canada use P/N 10953479)
Adhesive, Weatherstrip

12345739

(In Canada use P/N 10953541)
Sealant, RTV Silicone


Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

D2118
Seal, HVAC Module to Body
1.3 hrs

Add
Actuator, Air Inlet Door - Replace
1.0 hr

This is a unique labor operation for use only with this bulletin. The number will not be published in the Labor Time Guide.




GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


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My buddys 06 had the same problem when you picked up on the bottom of his interior blower motor box down by the floor on the pass side, warranty work repaired and resealed that box, problem fixed. His was like that since new and only got worse.

My buddys 06 had the same problem when you picked up on the bottom of his interior blower motor box down by the floor on the pass side, warranty work repaired and resealed that box, problem fixed. His was like that since new and only got worse.

I am out of warranty, so I want to fix the stupid thing myself....go figure, GM cannot seal a blower HVAC box properly, and they have been making automobiles how long????


Anyone know where I attack this problem from, they cowl outside under the wipers, or glovebox, and underneath passenger side? How does one remove this box and seal it up with silicone, etc????

I cannot take the whistle...


Cheers,

Push up on the pass side blower box under the glove box and see if it gets quieter. Try to narrow it down to the area and then there are different ways to fix it.

Push up on the pass side blower box under the glove box and see if it gets quieter. Try to narrow it down to the area and then there are different ways to fix it.

Hi Jeazor,

Thanks for your reply,

Thats exactly what I did, was push up on the whole box, with the motor spinning, and the harder I pressed, the quieter it got, but I can barely get my head under there so that is why I am not sure where is the best point to go into the trouble zone?? It is in a very S****y location to get to....

Yeah I know what you are saying, im a fat boy so gettin under there is tough,lol. Anyways you could tear the whole dash apart and I mean to get to the box you have to tear the whole dash pad apart, thats the bad news. The good news is to save alot of headaches I would just take some of the area apart and try to shim that box up with something firm to quiet it down, to be honest with you what we did was take a rubber from the fron cat exhaust hanger and shoved it under the box and it sealed up great, and then when he was layed off this fall he took it in to have the dealer do it right, which they tore the whole dash apart and resealed the box correctly. But the rubber work to, your choice.

james

Yeah I know what you are saying, im a fat boy so gettin under there is tough,lol. Anyways you could tear the whole dash apart and I mean to get to the box you have to tear the whole dash pad apart, thats the bad news. The good news is to save alot of headaches I would just take some of the area apart and try to shim that box up with something firm to quiet it down, to be honest with you what we did was take a rubber from the fron cat exhaust hanger and shoved it under the box and it sealed up great, and then when he was layed off this fall he took it in to have the dealer do it right, which they tore the whole dash apart and resealed the box correctly. But the rubber work to, your choice.

james

So you used rubber clamps from the exhaust and wedged it somewhere? This then supported the box and held it up? Where did you wedge it, which side? It could not have been in the center as that is where i push up with my hand, the onlything below it is the floorboard in the passenger wheel well?

As far as warranty, I guess it was under the 3 year 36K warranty?

I now have 41K so mine is up, unless there is a TSB or something?

Thanks again,

we used a rubber from the front hanger when we changed his exhaust system out,lol. Not right but it work, um i dont remember exactly where he put it but his truck is a bucket seat truck and it was just on the other side of the console on pass side under that black box. You couldnt see it, actually i think it was wedged up the side of it somehow, I guess you just need to find something to shim it with and then find a place to wedge it. Sorry im not much more help.

we used a rubber from the front hanger when we changed his exhaust system out,lol. Not right but it work, um i dont remember exactly where he put it but his truck is a bucket seat truck and it was just on the other side of the console on pass side under that black box. You couldnt see it, actually i think it was wedged up the side of it somehow, I guess you just need to find something to shim it with and then find a place to wedge it. Sorry im not much more help.

Thanks for the idea......I Will give it a shot.

As far as tearing the dash apart if I have to, can you only take one side of the dash out, or does the whole dash, driver side and all have to come out to seal this box properly?

Cheers

From what i can tell the whole dash needs to come out to get to it easily, i would TRY very hard to work some object up there to wedge and help seal the area leaking. Good luck and let us know how you made out.

Will Do,


Thanks,

I have actually had this problem since new. High pitched noises are hard to isolate.

It turns out my problem is a nosy two year old who kicks the window handle and cracks it. I have not found a fix to my problem yet, because when I tie her legs together she screams louder than the whistling noise I was trying to fix.

Good luck!

As soon as the weather gets better, I will try to locate and fix this air leak in my HVAC box.

I wish I could have had GM fix there "own mess" (HVAC box should not have air leaks in this day and age, and on such an expensive vehicle, my 92 GMC sierra never had it, go figure), but I bought the truck 4K miles out of bumper to bumper, and old owner never had the sense to have it fixed.....