just bought everything to install ac and installed it blows air now i need to charge the system im trying to retrofit from r12 to r134 and was wondering if theres any extra steps since everything was out of the system i bought. and my compressor not sure if the front pulley spins i tried by hand it didnt work but the actual belt pulley spins is there a way i can test if my compressor works before i add refrigerant and oil.