A person licensed as a contractor under this chapter may not:
(1) perform or offer or attempt to perform an act, service, or function 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 or is exempt by rule under that chapter; or
(C) defined as plumbing under Chapter 1301, unless the person holds a license under that chapter; or
(2) use the services of a person to assist in the performance of air conditioning and refrigeration maintenance work unless the person is a:
(A) registered or certified technician;
(B) licensed air conditioning and refrigeration contractor; or
(C) student described by Section 1302.502 who performs the work in that capacity.