I have a theater with an antique carrier condensing unit, actually 2 condensing units for their original theater. The theater started out with one screen and now has around 30, the original seated around 800 people and has an antique carrier ahu with 2 condensing units I cant remember right off how many tons each unit is, for heat there are "duct heaters" (basically unit heaters) in line with each of the three duct trunks. Anyway the compressors are both semi-hermetic with mechanical unloaders on 2 of the 3 heads. Well this spring on the second stage condensing unit I noticed the one head was cold weather unloaded or loaded, I suspected bad valves, so I got a new valve plate was surprised I could still get parts. I took off the head and valve plate and found I was correct, bad suction or actually no suction valves. On closer inspection I found one set of suction valves had broke off and was gone you could see where they had wore on the valve plate, the second set of suction valves however were never there from the factory there was no wear what so ever on the original valve plate! I was a little nervous of where the broken valves were or would end up, well later on I found the system was not working quite right again, could not adjust the txv, ordered a new txv, wondered if possibly a piece of the suction valves got into the txv, took the old one apart, found no foreign pieces but when I replaced the liquid dryer found most of the missing suction valves. Has anyone else had experience on these older carrier split systems missing suction valves?? I had a heck of a time getting the head to seal, tried different gaskets torqued the head to specs and could not get it to seal, finally used an automotive silicone type sealant for heads, and oil pans and finally got the system sealed up. Kinda fun working on and still getting parts for a system this old.