Performed heater check on three Carrier gas furnaces. These systems have all been converted to propane. Checked electrical, mechanical, safety, and performance of the systems. Drain lines were cleared and treated. All return and supply plenums are clean. Blower wheels are also clean. Igniters are operational and in value. Inducer motors are running at normal amperage. All systems are in good condition. Systems are running at the time of departure. See attached checklists for full tune-up details.