I put in a new condensing unit back in 2003. The customer called and said that it is making noises when it starts up. I went and listened and it makes a kind of a knock when it starts up. It runs quiet and fine after the first couple of seconds. I don't think it has a expansion valve. Someone else installed the furnace and coil. I am sure that they are matched as to size.
Anyway the condensing unit is on the ground and the evaporator is in the attic about 10' higher than the condensing unit. I came horizontal out of the condensing unit about 2' horizontal, then straight up about 10' then went horizontal ( and maybe slightly up hill) about 8' to the evaporator.
Could this cause the compressor to slug. I called the distributor that I got this from, and they said you need S-traps on 20' of rise. However they thought it might be a good idea to put one this system.
I also looked at a book from a copeland seminar I atended several years ago. It said that on 3' to 4' of vertical rise to put a P-trap by the condenser unit. Do any you do this. Any thoughts?
I am going to go back and make sure as to whether it has an expansion valve or not. It is in the attic and will go when it is not so hot.