Your Dutch Star should have multiple return vents and discharge vents in the ceiling. With the rear air off and the front air on, measure the temperature of the air of return air vent. Then measure the temperature of the discharge air vent; you should have allowed the unit to run for a good 5 minutes and have about 20 - 25 degrees difference between these readings. What reading are you getting? If after several hours these reading change drastically then your coil may be freezing up. Let us know the test results.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7