With this information in mind, a great deal of care must be taken in locating leaks in systems containing the less common refrigerants. With systems containing R-14, it is going to be tough to find a small leak.EVACUATIONThe proper evacuation of any system is in all probability the single most important phase of the repair. It is even more important to give any cascade system a thorough and complete evacuation, as the success of the repair depends upon this most important phase.Any time a system has been entered or a leak occurs and has been repaired, there is a good possibility that moisture and some noncondensables have entered the system, and they must be removed. Most low sides on cascade systems operate in a vacuum and if a leak occurs on this side of the system you can have a very real problem with moisture. Most second and third stages of a cascade system will not operate properly if the moisture content of the system is above 2-3 parts per million. THE SYSTEM MUST BE DRY:The triple evacuation method is preferred, rather leaving the system on a vacuum pump over night. It can be accomplished in less time, and other phases of the repair can be done while evacuation is in progress. Furthermore, you are there on the job, should a problem occur with the pump or any of the other components involved with this procedure. If this procedure is left unattended overnight, there are too many unknowns that can cause a failure of the repair.