* Age and Weathering: 1999 Suburbans are now over two decades old. Exposure to the elements (sun, rain, snow, extreme temperatures) causes the plastic components of the handle (especially if it's not a chrome or metal version) to become brittle and prone to cracking. UV radiation is a significant factor in this degradation.
* Repeated Use and Stress: The door handle is constantly subjected to stress from opening and closing the door. Over time, this repeated stress can lead to micro-fractures within the plastic, eventually culminating in a visible crack or complete breakage.
* Impact Damage: A minor bump or impact, perhaps from a shopping cart, another vehicle, or even a forceful door slam, can cause unseen damage that weakens the handle, making it more susceptible to cracking later. Even a seemingly minor impact might create hairline fractures that are only revealed after further stress.
* Material Defects: While less common, manufacturing defects in the plastic molding process could create weak points in the handle that are more prone to failure.
* Freezing Temperatures: Water getting into the handle assembly can freeze and expand, putting pressure on the internal components and potentially causing cracks in the handle itself or the surrounding plastic.
* Improper Repair: Previous attempts to repair a damaged handle may have weakened the structure, making it more prone to future breakage.
In summary, the failure usually isn't a single catastrophic event but rather a culmination of these factors over the lifespan of the vehicle. The plastic material simply wears out and becomes less resilient to stress.
