I have a Nordyne furnace approximately 13 years old. At times the furnace will not come on and I have to go and reset the rollout switch. We have discovered that when we leave the furnace cover off there isn't a problem. Our furnace repair man advises that he thinks the rollout switch needs replacing. How do I find the correct replacement part for this furnace ?

Roll out safety is probably OK see what is causing it to trip? Too much heat in the burner area?

Not enough combustion air? Lots to check... fix the problem, not just band aide it