2003 Chevy Tahoe blower will not turn off

You may be experiencing one of two faulty components. First I would check the blower motor relay located in the engine compartment fuse panel. This relay may have a stuck contact which is continualy sending power to the blower motor. An easy way to check this is to swap this relay with an identical relay located in the same fuse panel. For example if your horn relay is the same as your blower motor relay, swap them and test the blower motor. If it works you have a stuck relay. If the relay is not faulty, you may have a failed blower motor resistor. You can test this with an ohmmeter or you can visually inspect it as these resistors tend to have burn marks on them when they fail. The blower motor resistor is located under the passanger side dash. Remove the black cover under the dash. Immediately behind it is your blower motor and resistor assembly. The resistor has one electrical connector that has 7 wires going that go to the blower motor and is usually held in by 3 small screws. Remove the 3 screws and the resistor will come out. Look at the resistor circuit board. If you see any burn marks on the circuit board the resistor is faulty.

If you don't have relay in the fuse box then more than likely you have the set up that incorporates the relay with the resistor. When your take out the resistor your will see the relay mounted next to the electrical connector on the resistor. If you see no burn marks you may try hitting the relay on the ground with a swift hit straight down. It should knock the stuck contact loose. Regaurdless if you can get unstuck or not it is more than likely this component that is failing as the relay and reisitor are really your only components that control power to the blower motor.