Ive been in the business for just about 40 years now, what I tell my customers when they come in for a low charged AC system is that they have a leak. Its somewhere in that system and if its not ready apparent but dirt sticking to the oil that's in there also, then what I going to have to do is a recharge with using the dye. I then explain that for X amount of dollars, Im going to recharge the system with using the dye and that will help pinpoint the leak that their system has in the future.. My recharge with dye is NOT a repair, its a detection tool and your system will degrade over time. When it quits blowing cold, come back in and see me. I will then give you an estimate to correct the current leak, but remember, your system can and will have future leaks because all the hoses and O rings are the same age and they will all deteriorate over time. I then explain that in the future they can have mechanical and electrical problems that will make the AC system not work and that it had nothing to do with the recharge/dye we performed today. I then show them how vulnerable their condenser is to road debris damage and that a recent puncture might mask their original leak their vehicle had. Once I explained all that to the customer, Ive never had anyone upset at me or thought I was trying to rip them off. Because its the truth and an educated vehicle owner now fully understands this. Like I tell them, cold air costs money unless its winter time..