My A/C is currently blowing hot air, so I decided I'd buy one of those R-134a cans and put it in. Put for some reason, I could get it on the service port (by the radiator) and it sprayed all over and I wasted the can. How in the heck does that thing snap on? No matter how hard I tried, it did not connect properly on the service port. I thought I was going to break my wrist. Any ideas on this? How do I attach that can?