Air Conditioner problems of the 2001 Dodge Ram 2500

The air conditioning system has been a major problem after the first year I purchased the vehicle. It did not cool. It was repaired with a new evaporator on 8/16/02. It was again repaired on 4/3/03 with another new evaporator. The next year it did not work and it was again repaired with a new evaporator on 6/2/04. On all these jobs the water separator was never replaced. Again on 5/24/05 I took the truck in and they said the condenser needed to be replaced for $507. 23. Assistance at this time was denied. I finally had my local certfied mechanics at countryside truck service in montville, OH look at it. They said the condenser was okay and there were no leaks in the system. They told me that the freon was low. They pumped the system down and filled it to required levels. The air conditioning is now working fine. At this time the tech told me that the water separator was never replaced and should have been each time a major component is replaced.