First you have to determine if the compressor is in fact running. The easiest way, if you can not hear it come on, is with an amp meter. Measure the current while the fan is on and then when the unit is calling for cooling.
If the compressor is working and not cooling I suspect you have lost the gas charge in the unit.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles