Do you know the part number for the fan switch?

Is there a site I could go to see how to change out a fan switch?

Hi, I have a Nordyne propane furnace model #MMHA-056AAHR-01. The problem I am experiencing is when I turn my furnace on it fires up and after it reaches temperature the the fan turns on to disperse the hot air throughout the house but only stays on for 10 secs and shuts of then trys again for anothe...