receive the first energy consumption data from the at least first sensor and the second energy consumption data from the at least second sensor;

determine, from the first energy consumption data, a first average energy consumption value corresponding to each of a plurality of time segments over particular predetermined time periods of the operation of the at least one HVAC unit;

determine first arithmetic ratios of the determined first average energy consumption values relative to a known or estimated first maximum average energy consumption value for the at least one HVAC unit to obtain first normalized load values corresponding to the each of the plurality of time segments in the predetermined time periods;

determine first maximum normalized load values among the normalized load values within each of the predetermined time periods;

determine, from the second energy consumption data, second average energy consumption values of the similarly situated HVAC units corresponding to each of the plurality of time segments over the predetermined time periods;

determine second arithmetic ratios of the determined second average energy consumption values relative to known or estimated second maximum average energy consumption values for the similarly situated HVAC units to obtain second normalized load values corresponding to each of the plurality of time segments in the predetermined time periods;

determine second maximum normalized load values among the second normalized load values within each of the predetermined time periods;

compare the first maximum normalized load values to the second maximum normalized load values by taking a fourth arithmetic ratio of the particular predetermined time period's first maximum normalized load value relative to the second maximum normalized load value for the same predetermined time period, wherein a compressor failure fault condition may be indicated when the fourth arithmetic ratio is outside a compressor fault threshold range; and