Armstrong Air of Columbus, Ohio, makes a wide range of both gas- and oil-fired furnaces providing residential and commercial heat. Since all Armstrong furnaces share the same basic components (fan, burners, heat exchanger and thermostat), there are common steps you can use to troubleshoot your Armstrong Air furnace model should you have any problems. Just remember to always shut off the fuel supply and turn off the electric power breakers before opening any furnace cover panels. When your troubleshooting is complete, turn on the fuel and power before attempting to start the furnace.
Gas- and oil-fired furnaces have open-flame burners to produce heat. If the burners are clogged, they cannot produce enough heat to make the circulating air warm enough. Open the Armstrong furnace and see where the fuel line is connected to the device inside. This is the burner assembly. Make sure there's no buildup of soot or other dirt clogging the burner outlets. Also make sure the gas or oil line has a free flow to the burner assembly. The furnace will also have a pilot light to ignite the fuel whenever the furnace starts. See if the pilot light (a very small blue flame) is able to burn. (It will go out when you shut off the fuel supply.) Turn on the fuel supply and make sure the pilot light will ignite.
No Air or No Warm Air
If the furnace will start and the burners will ignite but there's still no warm air, check the heat exchanger for any clogging or interference in the air flow. The heat exchanger is a device where cold air flows in over the burners and warm air flows out. Also, turn on the electrical power and see if the blower fans operate. Make sure the blower fans are clean of any built-up dust and dirt.
Inspect the wall thermostat unit to determine if it is functioning properly. Turn the unit to "fan only" to see if the fan operates. If the fan will not operate along with the furnace (and possibly an attached central air conditioner unit), then the thermostat may need replacing. Some thermostats require batteries. Check the batteries and make sure they are not exhausted. Always replace thermostat batteries at least twice a year. When you change the clocks at the beginning and end of daylight-saving time, change the thermostat batteries then.