My bedroom a/c was under charged from the factory. I fixed it and been good since. 18 to 19 degree split on high speed and 22 deg on low speed.
Supply air temp minus return air temp.
If your getting a good delta split then it's doing all it can and other measures need to be taken. Close all shades, cover vents and shylights, seal any openings electrical and mechanical, seal underbelly, insulate if possible, camp in the shade, lastly add another a/c unit.
2014 Palomino Columbus 3650TH
435AH 12V VMax Charge Tanks, 520 watt Monocrystilline Solar Array, Morningstar MPPT TS-60 CC,Morningstar Remote,Cotek True Sine Wave Inverter,Cotek Remote Controller,50amp Progressive Hardwire Surge Protector
2015 Dodge 3500 6.7L 4X4
2011 CanAm Commander XT 1000