You people have it all wrong.
A tenant owning considerable back rent in an El Paso house was served by the property manager with an eviction notice for non payment of rent. When the tenant did not respond the landlord visited the premises and determined that the tenant had vacated the premises and abandoned their personal property.
Landlords don't get to make that "determination" without going to court first and getting a writ of possession.
Upon the belief of abandonment the property manager had the locks changed.
I'd be firing that manager and getting one that knows the state laws.
After the locks were changed the tenant contacted the landlord requesting return of personal property, which is still located within the premises. Under Texas housing law what are the property owner's rights and obligations with abandoned personal property in this situation?
Simple. At this point the property owner has no right to keep the tenant's personal property.
Must these items be returned to the tenant upon request?
Can the landlord require payment of past due rent to release the items to the tenant?
Sure, he CAN. But not without risking dire financial consequences if he gets sued by the tenant or arrested for theft.
Apparently, the items stored within the house have some commercial value as the tenant wants them to open a business.
Here's the Texas statute that applies here.
If the owner or property manager doesn't understand it, then somebody needs to hire a lawyer to explain it.
Warning: Legal issues are complicated. Explanations and comments here are simplified and might not fully explain the ramifications of your particular issue. I am not a lawyer. I do not give legal advice. I make comments based on my knowledge and experience. I guarantee nothing. If you act on my comments without the advice of an attorney, you do so at your own risk.