* Only one fan speed works (usually high): This is the most common symptom. The resistor controls the different fan speeds; if it's faulty, only the highest speed (which often bypasses the resistor) might function.
* No fan speed works: In some cases, a completely failed resistor can prevent the fan from operating at all.
* Intermittent fan speeds: The fan might work at some speeds but not others, or it might randomly switch between speeds.
* Burning smell: A failing resistor can overheat and produce a burning smell from under the dashboard. This is a serious indication of a problem that needs immediate attention to prevent a fire hazard.
In short, a bad blower motor resistor limits or eliminates your ability to control the speed of your cabin air blower fan. While it won't affect other systems in your Trailblazer, it will make the vehicle uncomfortable, especially in extreme weather conditions.
