Hi hladotech

in your photo
you have horizontal pipe (No.1) inlet then vertical goes up(No.2) then horizontal pipe to condenser (No. 3)
and your check valve lower than in let to condenser inlet pipe
so oil and liquid ( gas become liquid at around pipe when it goes to condenser ) block the discharge pipe

To solve that you have 2 option
1 ) put check valve (angle type) between 2 and 3
2 ) put 2 pipe in discharge ( S=S1+S2) S1= 1/3S & S2=2/3 S
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