Why does the technician need to pull out my indoor coil to clean it?
Your coil is probably so impacted with debris, that cleaning it in place would be a waste of time and money. Your coil needs to removed from the air handler and cleaned outside to clean it effectively. This will get your coil as close to new conditon as possible which will provide energy savings and help prevent future conditions for mold or bacteria growth. It is not recommended to pull a coil if the coil looks severely rusted. There is a risk that the new cleaning will remove corroded metal or debris which is just holding back the refrigerant charge.