AC failure & "evacuate" the AC system

(re: 96 Eagle Vision TSI) Can someone answer the following questions regarding A/c.1.) What is the proper diagnostic strategy (if there is one) to determine conclusively if the evaporator coil is bad (since it cannot be accessed easily. 2.) If one says that they are going to "evacuate" the AC system (clean debris out), what or where do they hook up the suction to conduct such a service? Is it valuable or effective?? thanks.
PS. My Eagle has been a joy to drive and a financial/mechanical nightmare to maintain: transmission, suspension, timing belt, water pump, and now, the AC. Got too much money in it to let it go.

(re: 96 Eagle Vision TSI) Can someone answer the following questions regarding A/c.1.) What is the proper diagnostic strategy (if there is one) to determine conclusively if the evaporator coil is bad (since it cannot be accessed easily. 2.) If one says that they are going to "evacuate" the AC system (clean debris out), what or where do they hook up the suction to conduct such a service? Is it valuable or effective?? thanks.
PS. My Eagle has been a joy to drive and a financial/mechanical nightmare to maintain: transmission, suspension, timing belt, water pump, and now, the AC. Got too much money in it to let it go.
Dye into system about $15 at Walmart ultraviolet light to check for leaks.Process of elimination to see if it is the evaporator.R134a systems are not as good as r12`s so you need to get all the air out,set of gauges,about $35 at autozone, vacum pump used to be about $100 at Mac tools.I think low side towards front of compressor is where to hook vacum. Autozone has Haynes air conditionig book for about $15 which should show you everthing.