If you're in Florida, he will need to register the judgment for enforcement in Florida before he can take any action against your assets physically located in that state (e.g., a car repo) or garnishment of payments or assets held in that state (be aware that it may be possible to garnish your "Florida" bank account if the bank, for example, is based in California.)
If you truly live in Florida, you can attempt to defend against any registration by pointing that out to the court hearing the attempt to register the judgment. Do not ignore any notices of an attempt to register the judgment. If you default in those proceedings, the judgment will be formally enforceable in Florida.

