Upon arrival unit was turned off. Customer stated the drain line was clogged and the secondary pan was filling up with water. Upon inspection we found the drain line was badly clogged. Purged the line with nitrogen and then flushed it with hot water with a small amount of evap coil cleaner chemicals. Had water pouring out outside with little to no obstruction. Vacuumed out the secondary drain pan and inspected the evap coil. Started the system and checked the refrigerant levels. Pressures were good and unit had 10* subcooling which is acceptable. Unit is working properly