Unit slightly low on refrigerant. Searched for leak with electronic leak detector and soap bubbles but was unable to pinpoint leak. Electronic detector reacting reliably near capillary tubes of condensing coil. So I do believe the leak is in the outdoor unit. I’m just not able to locate exactly where it is at. At this time, I’m going to recommend a fluorescent dye search. Where fluorescent dye and refrigerant is added to the system. System is then allowed to operate. After 2 to 3 weeks, we will return to complete fluorescent dye leak search. Of course, once the leak is located, we will then determine the next step to take.