(a) Except as otherwise provided by this subchapter, a person may not act or offer to act as an air conditioning and refrigeration technician unless the person is registered or certified under this subchapter.
(b) An air conditioning and refrigeration technician registration or certification is valid throughout the state.
(c) A person is not required to obtain an air conditioning and refrigeration technician registration or certification if the person only assists a licensed contractor in performing:
(1) the total replacement of a system; or
(2) the installation or repair of a boiler or pressure vessel that must be installed in accordance with rules adopted under Chapter 755, Health and Safety Code.