Have you ever seen a 7/8" suction line plug up in the middle?
On 5 meat cases on a large supermarket rack with R-22 in operation for ten years. Suction at two of the cases was 35# while at 3 cases it was 100+# (lucky to have a scherader at each case). Have had very few problems on this rack, never a compressor change, very few leaks over the years. The 5 single deck meat cases are tied together with a suction header that starts at 1-1/8" and goes down to 3/4" with no valves in between. I pumped it down. The 100+# cases would not pump down until I started to remove liquid/gas mix from it with hoses. Then all at once it equalized. I cut open the line. It was clean. I changed driers on the rack.
It had happened the week before, but by the time the other tech got there, it had cleared itself, so he just thought it had been stuck in defrost or something. I guess it must have been a wax/moisture glob. But how?