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Robert
Robert, ASE Certified Master
Category: Dodge
Satisfied Customers: 4291
Experience:  Dodge Master Certified, Dodge Sprinter Certified
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2011 Dodge Ram 2500. I have a very annoying rattle from

Customer Question

2011 Dodge Ram 2500. I have a very annoying rattle from behind my dash. Center or passenger side area. I have the dash almost completely apart. I believe the noise is coming from behind the HVAC system. What is back there that could cause this rattle and how might I fix it?
Submitted: 7 months ago.
Category: Dodge
Expert:  Robert replied 7 months ago.

Hello, welcome and thanks for asking your question. My name is*****'m a Certified Auto Technician with 29+ years experience. I will do my best to assist you. please keep in mind that I may need to ask questions of you before I can answer. When you reply please feel free to add as much detailed information as possible pertaining to your concern.

What type of rattle are you hearing? When does it rattle? Going over bumps??

What do you need to do to duplicate the rattling noise?

Customer: replied 7 months ago.
It is a rattle, what types are there? It sounds like something is loose rattling against another object.
It does not rattle over bumps, but it rattles most times at a low rpm; 30 mph kind of speed.
Duplicating the sound is easy by simply driving it. It is there most of the time but especially at the lower speed and rpms'
Expert:  Robert replied 7 months ago.

The rattling you are hearing is most likely something outside the vehicle under the hood tapping or rubbing on the firewall causing the noise you are hearing.

There really is not anything inside the vehicle forward of the HVAC box that can rattle. The HVAC box is mounted directly to the firewall with a sound deadener pad placed along the entire inside of the firewall. This silencer pad does a good job of quieting noises that can happen from inside the vehicle.

At this time, I recommend to look under the hood against the firewall in the area of concern and look for signs of components (hoses, wiring, etc) that can be making the rattling sound that you are hearing...

It is possible for something INSIDE the HVAC box to be rattling, could be a door rattling. What I would do is try changing the HVAC modes and temperature when you are hearing the rattling to see if you can make it change. IF the rattling changes when changing modes of the a/c start looking at hvac doors and actuators to be the cause of the rattling sounds...

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

Customer: replied 7 months ago.
Ok, I will give that try and let you know. Thanks
Expert:  Robert replied 7 months ago.

Sounds good. Let me know if you have any follow up questions...

Thank you,

Robert

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Customer: replied 7 months ago.
I went out this morning to see what I can find. There does not appear to be anything as far as hoses or wiring that are rattling against the firewall. Lets assume that perhaps one of the actuators or doors is the problem. I can see where there are 3 actuators right out in the open just behind the dash components; but the sound seems to be coming from the backside near the firewall. Is there an actuator on the other side next to the firewall? What will this mean as far as fixing it?
Expert:  Robert replied 7 months ago.

IF the vehicle has DUAL ZONE cooling/heating, there will be one actuator on the backside between the HVAC box and the firewall. If this is the case and that is the one making noise you would need to pull the dash and the hvac box for access to replace this actuator. If your vehicle has single zone a/c then there is no actuator back there....

Keep me posted...

Thank you,

Robert

Customer: replied 7 months ago.
Only problem is whether that is the problem or not. From what I have read on various forums, the actuators make a clicking noise when broken and there is usually a problem with improper air delivery. Mine is a distinct rattle, like something is rattling against something else; and I have no issues with the hvac systems functionality.
Really sucks. I have the truck for sale, and the last people would have gladly purchased it, but only if I get rid of the rattle. It is that noticeable and annoying.
Expert:  Robert replied 7 months ago.

Correct, failed actuators cause a clicking noise.

Is it possible for you to drive the vehicle and make a video of the rattling sound and post it here? If I could hear the noise for myself, I may be able to offer up a solution...

Keep me posted...

Thank you,

Robert

Expert:  Robert replied 7 months ago.
Customer: replied 7 months ago.
Here is a video link of my noise via google drive.
You can see when I press my thumb against the hvac it goes away temporarily.
https://drive.google.com/file/d/0B2FX4sghBIqaNnBQMTBhWFhSTFU/view?usp=sharing
Expert:  Robert replied 7 months ago.

Ok from hearing the noise, it appears that the noise is occuring when the HVAC Blower Motor is on high speed, does this rattle change with different speeds of the fan? I'm assuming that the vehicle is sitting still and not running, am I correct in this assumption?

It seems that the blower motor assembly is off balance, have you removed the blower motor for inspection?

If not, let me know if you need instructions on how to remove the blower motor assembly.

Customer: replied 7 months ago.
No.
The truck was moving at low speed ( aprox 30 mph) The Fan was in the OFF position.
Expert:  Robert replied 7 months ago.

Ok, wow, let me go back and listen to that again....

Expert:  Robert replied 7 months ago.

was that on a smooth road?? Do you have all terrain or mud tires installed?

Customer: replied 7 months ago.
Nice, smooth road. I can make the noise in my driveway sitting still too. Its like a certain RPM is what makes it rattle.
Expert:  Robert replied 7 months ago.

Do you feel that same vibration throughout the truck? It still sounded like the fan blower was running.... strange

can you duplicate the noise in your driveway and record it again and post it here... I have some ideas but the more video you can provide the better. Maybe take some video from outside the vehicle with the engine running and you duplicating the sound...

Keep me posted...

Thank you,

Robert

Customer: replied 7 months ago.
You won't hear this noise from outside the vehicle, its a diesel.
I don't feel any vibration, I just hear this constant rattle from the HVAC area, especially at that 30 mph speed.
It does not rattle at Idle in park; but when you put it in reverse, then the rattle starts but it is faint. Once your up to 30 mph, then it gets consistent and louder. At highway speeds it is only heard intermittently, but it is there.
Turning on the blower fan and moving the settings makes zero difference.
Expert:  Robert replied 7 months ago.

From looking your video over again it actually appears that you have found the problem area, all you have to do is to figure out what must be done to stop the rattling. When you press that area and stop the rattle it seems that you are either pressing on something behind the area stopping the noise or the noise is the two halves of the hvac box rattling against each other. What if you try to wedge something in between the upper and lower halves to see if you can get the rattle to stop without the need to press with your fingers? If you can get creative and find something (Cardboard, plastic piece, foam strip, etc.) to wedge between the upper and lower halves of the box, maybe you can make the noise stop so this way you can at least have a better chance of getting this vehicle sold...

Keep me posted...

Thank you,

Robert

Customer: replied 7 months ago.
Well, yes I have tried a few things as you suggest, but it seems to only stop it for a few minutes and then it comes back. Very frustrating to say the least. I may have to try some other attempts.
Expert:  Robert replied 7 months ago.

If you can get to a couple of the screws that secure the upper and lower sections of the hvac box, try loosening them a bit so that you can get a screwdriver wedged between the two halves. Open the two halves up enough so that you can wedge some foam strips in between. Then retighten the screws and pray....

Feel around in different areas to see if pressing different areas causes the same result. Another thing that sometimes is good at helping with rattles is mastic foil patches. These patches are a foil patch backed with a tar like substance that sticks well and is a good sound deadener...

With this rattle you will need to think "outside the box" to find something that will help to get the noise to stop...

Also try to recheck the torque of all fasteners in the surrounding area including hvac component fasteners, dash panel fasteners, etc... Something is bound to help the rattle...

Keep me posted...

Thank you,

Robert

Customer: replied 7 months ago.
Ok. I will give those options a try in the morning.
Expert:  Robert replied 7 months ago.

Sounds good.

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

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