Adding Refrigerant to LG Mini Split (Trim Charge)

New to this forum so please forgive me if this issue has already been addressed... I recently installed an LG mini split (ls243hlv3) at our cabin here in Colorado. The system is pre-charged for a line set up to 24.5 ft. After that, you need to add an additional 0.38 oz per foot. My line set purchased was 35ft. of which, I trimmed off about a foot after running it to the proper location. After evacuation and vacuuming down the line set, and checking for leaks (there were none), I added about 3.61 oz of refrigerant to account for additional length of line set.

Here's my question: I'm not getting the hot hot heat out of the indoor unit comparable to other mini splits I've installed. The outdoor unit ice damned once, but I had not cleaned the air filter in 3 months (which I think caused that issue). I don't think I have a leak after checking them. I think I might have undercharged the system as I did not account for the 2.5ft of line set that's attached to the indoor unit. Can I put the system in cooling mode, hook up my gauges, and simply add refrigerant to the system until it is at optimal psig (120 - 135 according to the manual)? Or, do I need to do a pump down procedure, vacuum the line set, and weigh in 2.5 ft of refrigerant from there?

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