Hi bro,
He used tap water or chemical to flash clean the chiller?
For me, I have done myself the flushing by using RO/DI water every few month.Beside that I have added a white cotton filter in front of the chiller's fan coil and change when the cotton discolored or clog. If the chiller man do the same as what I did than I will not call for a chiller service liao.