My freedom 80 2 stage furnace is acting up.After many service calls by a Service Tech,nothing is solved. I turn down my thermostat at night to 15 deg.C. and up in the morning to 21 deg.C. By doing that, only the exhaust fan kickes in and not the burner. The pressure switch and thermostat has been replaced,still no burner. The only way to get heat is to switch off the main furnace switch-wait 5 minutes and I get heat.The Technician checked all posible avenues-no answer. Do I need help-you bet I do. Thank you.