The cold and hot water coil is the most important part of the fan coil unit in terms of function; that is to say, the cold and heat energy possessed by the coil must be transferred efficiently into the air. Therefore, the surfaces of the pipes and fins of the cold/hot coil must always be maintained in a normal condition. Generally, cold/hot coils are made from copper tubes and aluminum fins. In terms of structure, various types of dust can easily adhere between the aluminum fins. If there's only a small amount of dust, cleaning between the aluminum fins will suffice. However, if dust accumulation is severe and blockages have occurred deep within the pipes between the aluminum fins, then cleaning alone won't meet the requirements. In this case, the coil must be removed, placed in clean water, and cleaned using a soaking method. Additionally, the ends and curved sections of the cold/hot coil pipes are the areas most prone to corrosion and leaks. Therefore, these parts should be carefully inspected and repaired promptly. This document was edited and organized by the Beijing McQuay Air Conditioning After-sales Service Center on September 23, 2011. Inspection methods for McQuay Air Conditioning fan coil unit coils.