I have one of the usual push on/snap on ac recharge connector hoses. I have tried to connect this to the low port (black cap near passenger firewall, but it will not connect. I push it on and can hear refrigerant escaping but it will not go all the way on but does not stay connected/sealed. I have used the same hose and connector on other cars with no problem.

 

Problem solved. Went out and bought a new connector hose with a METAL connector and built in guage. Snapped/pushed it on and it held like a dream. Pay a little more and get a metal connector. The plastic ones are so-so o.k., but the metal ones snap on real easy.