Forum

A. Check filters in the indoor unit. If filters are dirty clean or replace.
B. Check to make sure there is no blockage around the indoor or outdoor unit.
C. Check for proper suction pressure.

1. Suction pressure should range between 60 and 70 PSI
2. If pressures are too high, you will have to remove small amounts by evacuating lines until suction pressure is in range.
3. If pressure is too low. You will need to add refrigerant. If the mini split unit “RUN Load Amps” are more than two times the stated “RUN Load Amps” on the label of the outdoor unit label, replace capillary assembly.
4. The mini split unit will also not cool in low outdoor temperatures. There are low ambient kits to help run your air conditioner in temperatures below freezing.

Read original blog post