A person registered or certified under this subchapter may not:
(1) perform, offer to perform, or attempt to perform an act that is:
(A) defined as the practice of engineering under Chapter 1001, unless the person holds a license under that chapter;
(B) regulated under Chapter 113, Natural Resources Code, unless the person holds a license under that chapter or is exempt by a rule adopted under that chapter; or
(C) defined as plumbing under Chapter 1301, unless the person holds a license under that chapter; or
(2) assist a person who is not a licensed air conditioning and refrigeration contractor in the performance of air conditioning and refrigeration maintenance work.