Yep, I have had that problem. My rear was not cooling. If you pull the cover off the top os the A/C, the larger line (suction) should be cold and sweating. Mine was not and the amp draw was not where it should have been. Changed out unit under warranty.
I got better temps, but not what I was expecting. I have had to put some sun shades up to keep the direct sun off the left side. That helped out the most. The radiant heat is the killer.
14 Ram 3500 DRW mega Laramie 4x4, 6.7 CTD
2014 Sandpiper 360PDEK