I have a 2004 grand marquis and i have problems
with the blower motor resistor i have changed it
two times and it works fine for a couple days and
after it only works on high can someone help me
You may need to replace the blower motor.
So either the blower motor is pulling too many amps for the resistor block or there is something in the air flow passage that is causing the blower to work harder to move the air.