If the RR window works properly and the LF window does not, the chances are strong that there is power to the switches and the problem lies between the switch and the window.

You can confirm this by pulling out the new switch and unplugging it. With the key on, check for 12V at one of the pins. If you have 12V at one of the pins, then the problem must be either the switch, the motor, or the wiring between the two.

Many of these window issues are intermittent due to contacts that are not clean.

They can drive you crazy. Ask me how I know.