I have yet to find one of those pistol trigger dispensers to work right yet! But I have had the cap assembly blast off into space once with a big BANG! Get the hose that screws onto the top of the can, with the gauge if you like. It will help. When refrigerant is being sucked into your system, the can will go cold. The only other thing I've found is that sometimes the last person to do a conversion will not remove the Schrader valve in the original fitting and that can cause a recharge delay. You would have to remove the retrofit fitting first to find out, but try what I told you first. Try Phoenix for hot sometime! 103* in the shade so far this summer. It will get hotter!