2020 comfortmaker air conditioner. Customer mentioned unit struggling to keep up on hot days. Current delta t is 18 degrees. Checked refrigerant charge. System currently operating with 8 degrees sub cooling, but evap coil is boiling off at 34 degrees. Filter is clean and registers are all open. Customer had ducts cleaned roughly 3 months ago and noticed this issue starting to occur. I set dip switches to maximize airflow and added an ounce of 410 to achieve 9.8 degrees of sub cooling. Coil is now boiling at 41 degrees and temp drop is 18 degrees. This should increase dehumidification to allow for more comfortable air with no issue reaching set point on the thermostat.
