I may have messed up... while charging I didn't have the rear AC turned on... just forgot. So while cruising around today with the front blowing ice cold I turned on the rear and it gets sort of cool. Now the front temp is blowing warmer. I haven't checked the sight glass again but my thoughts are that I should have had both running while charging so I get the correct level of refrigerant to run both the front and rear units. Correct? Not sure how or if they are separated when you engage the switches.