Whistling from the HVAC System

Tiny
SUBE5186
  • MEMBER
  • 2010 CADILLAC SRX
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 7,000 MILES
I own a 2010 Cadillac SRX Premium, 3.0L AWD. I'm getting an intermittent whistling sound from the HVAC system when the heat or A/C is turned on. It's related to air flow, because the pitch and intensity of the whistling varies with changes in the fan speed. It's most prominent when set to "Auto". When heard, the sound is constant. However, the problem itself is intermittent. I've tried opening and closing the recirculating vent, changing the temp and switching from "Auto" to "Manual". None of these affect the whistling. I've checked all of the vents (including the one in the glove box). I opened and closed them all. It makes no difference what position they are in. This would seem to indicate that the problem lies in the ductwork, as opposed to the vents themselves. The sound is emanating from somewhere "inside" the system. Thank You
Wednesday, January 26th, 2011 AT 5:34 AM

8 Replies

Tiny
DOCHAGERTY
  • MECHANIC
  • 9,603 POSTS
This is a warranty issue. Schedule an appointment with the dealer straightaway.
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Thursday, January 27th, 2011 AT 1:27 AM
Tiny
SUBE5186
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  • 5 POSTS
Already did that. They had it for several days. They tested the HVAC system and found everything to be within spec. They are stumped. Any suggestions.
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Friday, January 28th, 2011 AT 4:22 AM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
What happens if you alter the airflow by opening or closing vent door(s), try and see if it changes. It may be considered a normal issue, or engineering may be working on a fix. Did the dealer staff compare it with a similar vehicle? This would be one of the last steps in determining whether it was characteristic of the system, or a potential issue.
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Friday, January 28th, 2011 AT 5:27 AM
Tiny
SUBE5186
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  • 5 POSTS
I already tried opening, closing and readjusting all of the vents, including the one in the glove box. The problem is intermittent, and therefore very difficult for them to duplicate. Of course, when I take the car home it happens like clockwork. The sound is NOT a high pitched wind noise like what you can get if you turn the blower up to full speed in some cars. This is a distinct "whistle" that comes and goes, sometimes fluttering when present. It's definitely related to AIR FLOW. It's not anything electronic. This is NOT normal in any car. A normal sound would NOT be intermittent. The problem is not present in other cars on their lot.
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Friday, January 28th, 2011 AT 2:00 PM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Considering that it is intermittent, the only suggestion I have is to make good observation of what the circumstance is when it occurs. This can be as specific as you can be, like temperature, speed, modes of hvac operation(recirc/defrost), etc. When it does occur, does it occur at speed as well as when the vehicle is stationary? To give you my background, I am, and have been a Cadillac technician for over 12 years. Intermittent problems are very challenging, and the most information that can be given for one to attempt to duplicate the concern, is critical in success of repair. With the concern that you are describing, it is more of a nuisance, than it is a safety concern, so operating the vehicle with the condition may be unacceptable, but not detrimental. If by chance you can demonstrate it to the dealer staff when it happens, then that provides the validity for them to address it at all odds. A suggestion to try as well, when it is making the whistle, does changing the blower speed change, or diminish the frequency at which the whistle occurs?
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Saturday, January 29th, 2011 AT 4:03 AM
Tiny
SUBE5186
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  • 5 POSTS
Yes, it happens when driving or stationary. I've already done everything you've mentioned. I'm very meticulous and believe in giving the Service Dept. As much detail as possible. I varied every setting on the HVAC system including fan speed, temp, recirculation, Auto, Manual, vents selected, etc. Changing the fan speed does change the frequency of the whistle. That's how I know it's related to air flow, as opposed to something electronic.

Just recently another online Cadillac technician explained that this is most likely caused by a faulty or improperly seated cabin air filter. I removed this filter and re-seated it. I've yet to have a chance to test this. When I do, if it still makes the noise I'll replace the filter. I'll report back to you with my findings. Thank you.
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Saturday, January 29th, 2011 AT 4:25 AM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Either do that, or remove the filter, and see if it still happens.
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Saturday, January 29th, 2011 AT 4:30 AM
Tiny
SUBE5186
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  • 5 POSTS
Yes, if re-seating it doesn't work, I'll remove it and see if that eliminates the whistle.
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Saturday, January 29th, 2011 AT 5:47 AM

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