My new-to-me 07 Denali (love this rig, btw) has an issue with the front blower motor. It will work intermittently, and will work all of the time as long as the controls are set to manual (no auto) and on high.

If you set the controls to Auto, it'll work for a while, then it acts as if it isn't getting enough voltage, it clicks, and runs at like 25% speed and isn't very effective.

I saw that there might be a tsb for this, but since this isn't under warranty, I hope there's an easy way to fix it.

Is it as simple as replacing the blower control module, and if so, any links to where that thing is located in the rig?

Thanks!

 

Correct me if I'm wrong but on the auto setting, the blower motor speed will vary in response to whether or not the inside temp is meeting your auto temp setting.

 

well, sort of. It does vary, but if you put it on high (or say, set the temp to 60 degrees or some low temp far below current inside temp,) it'll run full blast for a while, but then it'll slow down, but not in a predictable way.

It doesn't go from like fan speed 5 to fan speed 2, then back up again as needed. Once it goes down, if it tries to go back, then it gets this "chunky" sound to it, like something's in the squirrel cage (but there isn't, it works fine at other times.) It'll stay like that until the rig is shut off for 15-30 minutes and back on, or it'll never happen if you just run it on full blast (hi fan speed, on manual setting (non auto) all of the time. So, you can either run it full blast and freeze to death, or run it on auto, be comfortable for a half hour, then bake. We just did a 3000 mile trip, and down south, it got to be an issue.

 

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The HVAC control module software may need to be updated. This is just a suggestion, not a diagnosis. I encourage you to have the vehicle inspected by a certified technician. They will be able to offer a more accurate diagnosis have a physical inspection of the vehicle.

Please keep us posted.

Louis
GM Customer Service