Can you put r12 in an r134?

No, you should not mix R12 and R134a refrigerants. R12 is a chlorofluorocarbon (CFC) that is being phased out due to its harmful environmental effects, while R134a is a hydrofluorocarbon (HFC) that is more environmentally friendly. Mixing them can lead to system damage, reduced efficiency, and environmental concerns. Always use the refrigerant specified for your system.