Hello! Welcome to justanswer!
Do you have 1 or 2 AC Compressors?
The small line has the orifice in it. Or it has an expansion valve. If the small line has nothing attached to it, it has an orifice. Take it off at the evaporator and find the orifice. Its there for sure.
This is the part you are looking for back there.... It should have an expansion valve and its plugged up... Heres a picture: