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Squealing noise coming from HVAC vents

jwoodall

By jwoodall
in Ask A GM Technician

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jwoodall Enthusiast

jwoodall

Posted
Posted

Hi all:

 

My truck is a 2009 Ext cab Silverado, and it has the auto climate control. Yesterday afternoon the squealing noise started. Seems to be from the right HVAC vent but I can't pinpoint for sure. Only seems to happen when I have the air circulating from the outside. If I turn the HVAC off, the squeal mostly goes away. Of course with it being so cold out I cannot turn the A/C on so it will not let me run with cabin circulation. Any ideas what happened?

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Just taking a guess here, but it sounds like GM cheaped out on grease in the blower motor bearings.

 

My '85 Monte Carlo used to do that in cold weather, when it was 10 years old. Removed that vent tube & sprayed lube in there, and it was as quiet as a mouse until it got sent to the crusher.

 

I highly doubt the newer motors are serviceable in any way though ...

dtspitcherguy Enthusiast

dtspitcherguy

Posted
Posted

I am not a technician, but I have a similar situation going on with my 09 GMC with auto and air intake. It has been cold in Ohio too but this started in the summer and has reached a maximum annoyance level. I have read several others that seem to have issues with the blower resistor. It seems to be a recurring problem with GM trucks. I have one ordered and will be replacing it. Hopefully it will work. Once I get it in and fixed, I will report back and let you know.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

The resistor won't cause a squeal - that issue causes several speeds to not work on a manual system. Not sure how the auto one is controlled - if I had to guess, it's via computer ... like everything these days.

jwoodall Enthusiast

jwoodall

Posted
  • Author
Posted

Thanks for the replys. Another important point I forgot to mention is that the squeal is also dependent on road speed. It starts about the time I hit 40 mph. So that also leads me to believe it is related to the outside air intake vent.

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