Yes Hookup is right, it is about 20 degrees. Check the supply temp coming out of the vent. Before I changed out my unit form a 13,500 BTU to a 15,000 BTU this year @ 90 degrees ambit temp, my supply temp was at 60 degrees, this means, I could not lower the temp any cooler then 73 degrees in the camper. Three weeks ago we were camping with temp in the low to mid 90's with high humidity and a heat index of 100 to 105 degrees, the new A/C systems air supply was delivering 45 degree, the unit satisfied the space temp set point and cycled off until it called for cooling again which by the way was not long before it came back on. You will notice that when the sun go's down you then have plenty of cooling capacity that's because the heat load has been reduced, and the A/C unit can keep up with demand. Camper leak air. Keep a clean filter at all times. If a filter gets dirty the motor works harder this is air restriction then it can or will affect the refrigerant circuit by dirt passing though the filter and collecting in the evaporator coil, again added air restriction. There is a chain reaction with heating and cooling system and in most cases a dirty filter will start it all.