The problem of dirt or debris blockage of the Hitachi air conditioning system's cooling coil or evaporator coil in an air conditioning system air handler, how the dirt gets there, what problems it causes,
Dirty air filter can be mistaken for a blocked cooling coil. Always check your air filter first. Replace it if it's clogged and dirty and check the filter regularly.
When the coil becomes sufficiently blocked with debris as to slow down the air flow enough, the coil may actually become so cold that the condensate forming on its surface freezes, completely blocking the coil. That's because the rate of release of refrigerant into the evaporator coil was designed with an assumption of a sufficient volume of air moving across the coil to keep it from becoming too cold.
Damaged Hitachi AC coil fins can occur on both the evaporator (cooling) coil and the outside condensing coil.
A dirty blower fan can be the cause of reduced airflow across the cooling coil and can even lead to coil icing.
in the duct system can interfere with proper airflow through the duct system, reducing air delivery into the building, and can be mistaken for a blocked or dirty cooling coil.