On our 2004 Marquis Sapphire, I have recharged the dash AC system a couple of times. I do not have the proper equipment and knowledge to do it right but I did purchase the hose with a gauge that gives some feedback. On our coach, I made the attachment to the line about one foot above the front slideout generator, behind and very near the front cap. I have added one or two small cans each time and it did make a difference. But at best, the dash AC will do little to cool a 45' long coach. If it's over 80 degrees inside the coach, I start the generator and set the three roof ACs at 70 degrees.