Customer requested service due to noisy coil. Checked operation on unit to investigate report by customer that there is a noise coming from the unit like something is out of balance or possibly loose. Inspected the blower compartment, blower housing and monitored the blower wheel while the unit was running. Cycled the unit on and off to watch it start from a stopped position. Service tech did not see hear anything out of the ordinary, no sign of vibration or rattling or anything loose. I also went to the outdoor unit and cycled that unit on and off a few times, there is nothing abnormal with the outdoor unit either. The house is very quiet, the unit is in the attic and sitting directly over the guest room where the noise is being heard, I believe it is just the normal sound but is carrying through the return and is causing it to be heard. Customer satisfied with diagnosis and will highly recommend Advanced Heating & Cooling.