Final answer:
The refill of CFCs or HCFCs in mobile air conditioners is restricted under international agreements such as the Montreal Protocol, in order to protect the ozone layer.
Step-by-step explanation:
The refill of chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) for mobile air conditioners is restricted. Under the Montreal Protocol, the production and consumption of CFCs and HCFCs have been phased out due to their harmful effects on the ozone layer. Hydrofluorocarbons (HFCs) are among the substances that have been developed as substitutes for the more ozone-depleting compounds. The protocol indicates a gradual move away from CFCs and HCFCs, with exemptions only for certain uses that do not have feasible alternatives. Despite HCFCs being less harmful than CFCs, their use is also being phased out to minimize their environmental impact.