condenser , evaporator and all hoses must be flushed with CTC before every gas recharge,,,,,,,,,compressor also must be flushed with proper compressor oil , ND R134a need ND-8 oil , and then filled with new oil in proper volume,,,,,,,,,,,,,,,dryier/filer must also be replaced on every gas recharge,,,,,,,,,,,,,,other wise wont get the desired output