2003 chevy caviler knocking noise under dash by blower motor

Sounds like the diverter door is bound up causing the motor to bog down under load. You'll need a manual for that job. It's a pain in the rear to get to.

Check blowers motor cage under dash sounds like it faulty

Try starting the truck so it makes the noise.
Then switch the air control to "fresh".
If noise stops, it is probably the motor that closes flap to recycle the cab air.
It would be found under the dash, under the glove box, & would need to be replaced.

This may be a defective blower motor shaft bearing , have a technician listen to it to confirm the problem is the bearing in the motor.

THE LOUD NOISE IS PROBABLY COMING FROM THE BLOWER MOTOR WHICH IS LOCATED IN THAT AREA. THESE SOMETIMES MAKE A LITTLE NOISE BUT IF THIS NOISE IS LOUD OR JUST DOESNT SOUND RIGHT, THE MOTOR COULD BE GOING BAD.

sounds like u have an electric mode door motor,in ur hvac housing stripped . move the mode selector to different positions to amplify noise an sort of control noise. u have a blend air door motor, mode position motor, for example inside air an outside air recirculating door motor, or defroster mode motor or actuate the heater position an u should b able to control noise by changing modes, thats wen u know u found it wen u can make the noise come an go. also one of ur selector positions is obviously not workin due to a stripped motor or broken blend door. good luck

This is a problem with the blower motor module. It needs replaced it is located on the passenger side under the dash by the blower motor. You can unplug this and it will turn off.

Check the blower motor resistor.It is on the passengers side by the blower motor under the dash.The resistor is connected to the blower motor and controls the blower speeds.They are known for going bad.Also check the connectors because they get hot and will melt.If they are melted then you will have to replace the connectors.You can get these from the dealership.Replace the blower motor resistor too.Hope this helps.Good luck.

Itmay be a foreign object inside the blower motor, a bar blower motor or your engine is bad, have a technician scan it to be shure.

Yea leafs and other debris can get in and cause the noise. Remove the blower, thoroughly clean the fins and reinstall. This should take care of the noise.