Can refrigerant R22 be mixed with R134A?

No, refrigerant R22 and R134A should not be mixed. R22 is a hydrochlorofluorocarbon (HCFC) refrigerant, while R134A is a hydrofluorocarbon (HFC). Mixing them can lead to improper system performance, potential damage to the compressor, and can also affect the efficiency of the cooling process. It's important to use the correct refrigerant specified for the system to ensure optimal operation and compliance with environmental regulations.