Owners of certain models of Thomas Built Buses were advised by the manufacturer that the air conditioning start a fire.

More than 6,800 school buses are thought to be affected by a fuse holder that may melt, according to the NHTSA recall. The air conditioning units are Carrier GENV EM-1 Evaporators installed in model year 2006 through 2011 FS-65, Minotour, MVP-EF, Saf-T-Liner C2 and Saf-T-Liner HDX vehicles. The buses were manufactured from Jan. 2, 2006 through Jan. 31 of this year.

Time, temperature and/or vibration can cause the fuse to loosen in the fuse holder. This can result in high resistance and arcing, which in turn could cause the fuse holder to melt and fire.

The recall campaign number FL-604 was issued by Daimler Trucks North America, the parent company of Thomas Built. Daimler Trucks was expected to notify owners of how to obtain a retrofit kit free of charge from Carrier next month.