Furnace won't lite but igniter is good

Aaac service heating and air found this bad draft motor Sunday. The furnace would not lite. The igniter was testing okay. The draft motor was rusted. It made no draft so the circuit board didn"t send power to the igniter. This is a 20 year old Rheem . If th e draft motor rusted like this there is rust in the heat exvhanger. This is an expensive repair and the exchanger may be bad. I would not fix it. Buy a new one. If it was 10 I would replace the motor. A 20 year old furnace will have other parts break soon and may not be safe. Never run a 20 year old gas furnace without a carbon monoxide detector in the house. Aaac service heating and air Mcdonough is open on Sunday.7708754113