Heat Pump - 4 Way Valve.

[icecube51]

A capiliary is a fixed oriface and will provide the same pressure drop with flow in either direction. An electronic expansion device will regulate depending on the mode.
A biflow filter can be used but usually only a strainer is needed
Brit

in addition whit the capillary there is the strainer,where inside is like a metal marble ho is correcting the flow ore amount of refrigerant.try and find an old unit and dismount it completely, open the parts as well. thats how i learned it in the old days. you understand the working parts better then.

Ice