It might be your resistor, does it work on 4 but not on 1,2,3? If so, you need a new blower motor resistor.
One can replace blower motor resistor on 2003 Nissan altima by removing the old using spanners and replacing it with a new one.
I actually have a brand new blower motor for a 2002 Nissan maxima. Its brand new, I bought it from Sandy Sansing Nissan in Pensacola, Florida thinking I needed to replace it, but it was actually my fan control amplifier that needed replacing. So if you need a new blower motor, I can ship you a new one for a bargain. I paid 219.00 for it, I'll let it go for 100.00. Email me at ebonysailor@yahoo.com
The car is to new to have it done yourself, you must take it to your nearest Nissan dealer.
To change the blower motor resistor in a 2002 Nissan Maxima, locate the blower motor resistor under the glove compartment on the passenger side of the vehicle. There is a clip that is depressed and then the resistor will slide out. Remove both ends of the resistor and then replace with the new resistor.
* Disconnect the negative battery cable * Remove the glove compartment and lower dash trim to gain access to the heater case and blower motor * Detach the blower motor cover and disconnect the electrical connector from the blower motor * Remove the blower motor mounting screws and pull the blower motor carefully out of the housing * If you are replacing the motor detach the fan and transfer it to the new motor
you need a new blower motor resistor
Locate the resistor under the dash attached on the blower motor housing. Disconnect the wire harness connector. Remove the resistor and install a new one.
I do not know what vehicle you are referring to but I just replaced one on a 1996 Nissan Sentra because the only speed that was working on the blower motor was 'high'. Underneath the glove box was a couple of screws that came out and the new resistor was put in. Two screws and done......... Most blower motor resistors are located close to the blower motor.
Remove the wiring harness from the back of the blower motor in your 1993 GMC 1500. Remove the blower motor retaining bolts. If the new blower motor does not have the fan attached to and you will need to remove the fan from the old blower motor. Reverse the process to install the new blower motor.
Remove the blower motor retaining nuts. Remove the wiring harness from the back of the blower motor. Remove the fan from the blower motor. Reverse the process to install the new blower motor.
Remove the wiring harness from the back of the blower motor. Remove the blower motor retaining screws. Remove the fan from the blower motor. Reverse the process to install the new blower motor.
Remove the wiring harness from the back of your 2001 Chevrolet Corvette blower motor. Remove the blower motor retaining bolts. Remove the blower motor fan. Reverse the process to install the new blower motor.