I have an olsen KAS100 that I bought used.. looks a little old with no manuals and can't find much on the net. The issue I am having is the unit will fire with gas on and burners will ignite, however, the circulation fan will not turn on. The burners will run for about 5 mins then shut down. If i direct wire the fan it will turn on.. any idea where to start? Anyone familiar with this unit? It is an overhead furnace 75,000 BTU. Thanks!