mike watch them while they work if you can. If they replace any thing they need to vaccum the system then add the coolant. most places will put a wax type hardner over the charge point to make sure its sealed tight. on hot days you will see frost on the cold line going to the house. as long as the hot line comming back is hot you know the flow in not obstructed. for cleaning coils use a pump type sprayer and get some coil cleaner from lowes or grainger. let me know if tex;s guy cant make it for some reason. Ive worked on large industrial units and can atleast find your prob or tell you if the repair man is full of it.