1. Diagnosis:
* Isolate the Problem: Is it just the motor not working, or is there a complete lack of power at the switch? Test the power at the switch and at the motor connector using a multimeter. If there's no power at the connector, the problem is likely in the wiring, fuse, or switch. If power is present but the motor doesn't run, the problem is likely within the motor assembly or regulator.
* Check the Fuse: Consult your owner's manual to locate the fuse for the power windows. A blown fuse is an easy fix.
* Test the Window Switch: Try the switch in other window circuits to see if it's faulty. A faulty switch is a common cause.
* Listen for Clicking: If you hear a clicking sound when you operate the switch, the motor may be seized or the gears stripped.
2. Accessing the Motor and Regulator:
This is the most labor-intensive part and varies slightly depending on the door. Generally:
* Remove the Interior Door Panel: This usually involves removing screws around the panel edges, disconnecting the window switch, and possibly unclipping some fasteners. There are plenty of online resources (YouTube videos are particularly helpful) showing this specific process for a 1991 Ford Explorer. Search for "1991 Ford Explorer door panel removal."
* Locate the Window Regulator and Motor: The regulator is the mechanical part that moves the window, and the motor is what drives the regulator. They're typically mounted together.
* Disconnect the Motor Connector: Carefully unplug the electrical connector from the motor.
3. Repair Options:
* Lubrication (If Gears are Sticking): If the motor is making noise but not working, you might try lubricating the gears with a light lubricant (like white lithium grease). This is often a temporary fix. Access to the gears may require partial disassembly of the regulator.
* Gear Replacement (If Gears are Stripped): Stripped gears are a common problem. You might be able to find replacement gears or a complete regulator/motor assembly online (eBay, parts stores, etc.). This usually requires disassembling the regulator and replacing the faulty components.
* Motor Replacement (If Motor is Burned Out): A burnt-out motor is less common but possible. Again, replacement is usually necessary, often requiring a new regulator/motor assembly.
* Wiring Repair (If Wiring is Damaged): Check the wiring for breaks, frays, or corrosion. Repair or replace damaged wires.
4. Reassembly:
* Install the Replacement Parts (If Necessary): Install new gears, a motor, or a complete regulator/motor assembly.
* Reconnect the Motor Connector: Carefully plug the connector back into the motor.
* Reinstall the Door Panel: Reverse the steps you took to remove the door panel.
Important Considerations:
* Safety First: Disconnect the negative battery terminal before starting any work to prevent electrical shock.
* Patience: This is a time-consuming project. Take your time and be careful not to damage any parts.
* Online Resources: YouTube videos and forums dedicated to Ford Explorers are invaluable resources. Search for "1991 Ford Explorer power window repair" for visual guidance.
* Professional Help: If you're not comfortable working on car mechanics, consider taking it to a professional mechanic.
Remember to always consult a repair manual specific to your 1991 Ford Explorer for detailed instructions and diagrams. The process might vary slightly depending on the trim level and door. Good luck!
