Mitsubishi Mini-split Branch Box question

Stoli

Residential 5 port Mitsubishi branch box: PAC-MKA51BC

If only 4 of the 5 ports are used, does it matter which ones? The install manual sort of insinuates that you should use A, B, C and D and leave E unused, although it sounds more like a recommendation than a requirement. My installer used A, B, D and E and left C unused, presumably because port E has a 1/2" gas line (the other 4 are 3/8") and one of the inside units was larger and required a 1/2" line. That way, he didn't need to install a 3/8" to 1/2" converter pipe.

GW

Does not matter which ports you use. Does not have to be sequential, at all. But, you have to select the correct addressing for the wiring. Every time I do a D box, too many months have passed and I can’t remember the exact process. It’s buried in my notes somewhere

Stoli

Cheers Gary. I appreciate you taking the time to respond.

Kybeans403

Thought its 15 and 51 (condenser first then box)

Stoli

Probably important to note that there may be differences depending on the models, but in my case, I have a newer MXZ condenser and the PAC-MKA51BC branch box with 4 indoor units hooked up, so the addressing setup is:

Condenser: 51 (SWU2, SWU1)
Branch Box:
  Address: 01 (SW12, SW11)
  SW1: Active ports (A, B, D, E) set to ON

That effectively addresses the indoor units to
A : 01
B : 02
C : (NOT USED)
D : 03
E : 04

Gets a little more complicated with multiple D boxes, but the manuals are pretty good regarding proper addressing setup.

** NOTE: I'm not a Mitsubish Tech. **