I took my car on a longer road trip over the weekend, about three hours each way, and noticed the air coming from the vents felt significantly weaker by the time I reached my destination. It started out ice cold but slowly lost its punch. When I turned the car off and let it sit for a while, it seemed to work fine again on the way back, but I am worried it is going to leave me stranded on a really hot day. I have been reading about how important it is to actually check the system instead of just refilling the refrigerant, but I have no idea where to start with diagnosing car cooling performance issues. It feels like one of those problems that is going to get worse the more I ignore it.