Does the coating affect the operating pressures of the A/C system?
A. No. Operating or head pressure has to do with operational factors in a sealed system, such as a weak or declining compressor. Improperly applied coatings applied to fin tube coils could mildly affect the ability to transfer heat to some extent, but not specifically head pressure. If there were any significant increases in head pressure, it would indicate some other problems within the unit.
