A big air handler has many controls that monitor and regulate its operation. These devices include thermostats, damper controls, static pressure sensors, enthalpy sensors, and smoke detectors. All are located in a rigorous environment: there are high levels of vibration, unusual temperature swings, and lots of dust, grease, and grime. It is only natural that delicate electronic and pneumatic devices become out of calibration in these conditions. Following the manufacturer’s recommended maintenance schedule can remedy problems before they cause significant unit dysfunction. This, in turn, can avoid operation of the unit for long periods of time at below peak efficiency.
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Excerpt from Energy Conservation Projects.