A method and computer program product for identifying one or more malfunctions in a locomotive air compressing system is provided. Some of the malfunctions may be correctable onboard a locomotive, and constitute onboard serviceable malfunctions, while the remaining of the malfunctions may only be correctable with the air compressing system being uninstalled and serviced at an off-board servicing site, such malfunctions constitute off-board serviceable malfunctions. The method allows monitoring responses indicative of a malfunction type that may be associated with at least with one of the following: a corrective action that may be performed onboard the locomotive, and a corrective action that may only be performed off-board the locomotive.