Upon my arrival I asked the customer to explain the problem to me. Customer had noticed that when the upstairs unit is turned on, which is a smaller tonnage then the downstairs, main unit, that the larger size outdoor unit turns on, and the smaller in size unit turns on when the basement unit operates. Customer thought maybe a mistake was made and that this was the reason for the problems they experienced several months ago. I explained the smaller in size unit has an inverter compressor and the traditional outdoor unit is actually larger. Everything is correct. Customer has no other issues. I called the installation manager to confirm that this would be written up as a courtesy call. No charge. Units operating normal.