Q: Reduced engine power, tire pressure symbol, and AC noises

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I had my 2008 Chevy impala lt for over a year. Ever since I had it, I had a yellow light on the dashboard that look like this : ( ! ) and a tire sensor symbol. Just about six months ago my car started to make knocking noises from the inside everytime I turned on the fan/AC/heat. Someone told me it could be the actuator or the fan stuck. I figure it was not important since they both worked. So today, I was driving in town when my car started to slow down and displayed a 'reduced engine power.' I had a oil change and new tires about a month ago. I'm not sure what the problem is. Why did it happen and how can I fix it?
My car has an automatic transmission.

Hello. From what you describe it would appear that your vehicle may be experiencing more than one issue. The exclamation mark and tire symbol come on when the vehicle’s tire pressure monitoring system is set off. This occurs when the system detects that the pressure has dropped excessively low, or that a fault with the system has occurred. Checking the tire pressure could determine if the tires need to be inflated or if there may be an issue with the system. This could be related to the recent tire service that the vehicle had. Knocking noises when the AC is activated could be a sign that there may be a fault with one of the AC system’s moving components, perhaps the blend door actuator or the blower motor. The power reduced light comes on when the vehicle is put into power reduced mode. When the computer detects an issue that could potentially cause damage to the engine or emissions components it will reduce engine power in order to reduce the possibility of damage to the any components. This can be caused by a wide variety of issues, ranging from a wiring issue to a bad fuel pump. Scanning the computer to see what trouble codes are present will likely shed some insight on what the issue or issues may be. As it appears that your vehicle is experiencing more than one issue I would recommend having a professional technician, such as one from YourMechanic, visit your location to diagnose what is setting off your warning lights and causing your AC noises.

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