Will this install without removing the door panel?

Access to the switch mounting points requires removing the inner door panel trim. Once removed, the switch pulls straight out and the new one seats into factory mounting points — no drilling or modification needed.

Do I need to test this before fully reassembling the door?

Yes. Before reinstalling trim and panels, connect power and cycle the window up and down a few times. Catches any contact issues while everything is still accessible.

What if the window moves slowly or doesn't respond immediately after install?

Check that the switch is fully seated in its mounting bracket — a loose seating can cause intermittent contact. If the motor itself is sluggish, that's a separate issue in the regulator or motor assembly, not the switch.