i have a 1999 explorer northface, rear drivers side door won't unlock inside or out all other doors ok. i can lift up catch on top of the panel no joy. worked 1 min then not. any ideas thanks steve H

Could be the window regulator (motor) inside the door. Could also be the contacts. Check for bad connection at wire connection at motor.

Forget the above remark, I misread your post. Check the electrical connection at the LOCK, not regulator. With a multi-meter, check for voltage when the unlock/lock button is pushed. If it is not present the problem is not with the lock. If present, replace the lock mechanism.

Does the little knob on the top wiggle when you try to unlock the door, or is it dead. If it wiggles, try flooding the mechanism with squirts of WD40, Sometime they get clogged up with dirt and debris and the lock cannot overcome the resistance.