1. Check the Obvious:
* Exterior Handle: Is the exterior door handle completely loose or broken? A broken handle will prevent unlocking. If it's loose, try tightening it if possible. If broken, you'll need a replacement.
* Key: Try the key in the lock cylinder. Sometimes a little WD-40 (used sparingly!) can help free up a sticky lock cylinder. Be careful not to overspray. Afterward, use the key repeatedly to work out the lubricant.
* Interior Handle: Is the interior door handle completely free to move? If it's broken or jammed, it might be preventing the latch from releasing.
2. Access the Latch Mechanism:
You'll likely need to remove the interior door panel to access the latch mechanism. This involves:
* Removing the panel: This varies depending on the specific door, but generally involves removing screws from the armrest, door pull, and possibly around the edges of the panel itself. Search online for a "1990 Chevy Astro door panel removal" video; many are available. Be gentle to avoid breaking any clips.
* Inspecting the linkage: Once the panel is removed, you'll see the linkage connecting the interior and exterior handles to the latch mechanism. Look for anything bent, broken, or disconnected. Try to gently work the linkage by hand to see if it's free. Sometimes a bit of lubrication (like white lithium grease, not WD-40) can help if there's binding.
* Inspecting the latch mechanism: Examine the latch itself for any obstructions or broken parts. Sometimes debris can get jammed in the mechanism.
3. Potential Problems and Solutions:
* Broken Linkage: If a rod or linkage is broken, it will need to be replaced. You may be able to find parts at a junkyard or online auto parts stores.
* Jammed Latch: If the latch itself is jammed, you might be able to carefully work it free with pliers (but be extremely careful not to damage the mechanism). A small amount of lubricant might help if there's no breakage.
* Actuator Problem (Power Locks): If your Astro has power locks, the actuator motor might be malfunctioning. This is more involved and may require replacing the actuator. This is usually the most expensive solution.
* Vacuum Lines (if vacuum-operated locks): Some Astro vans might use vacuum lines for locking. A leak or issue in the vacuum system could prevent the door from unlocking. Check these lines for leaks or damage.
4. If All Else Fails:
* Professional Help: If you're uncomfortable working on the door yourself or if the problem remains unsolved, take your Astro to a qualified mechanic or auto body shop. They have the tools and experience to diagnose and repair the problem.
Important Safety Note: Before you begin any work, disconnect the negative battery terminal to prevent accidental shorts or shocks. Always be careful when handling tools and working near moving parts. If you're unsure about any step, it's better to seek professional assistance.
