How to Troubleshoot a Goodman Furnace With an Indoor Blower

Turn up the thermostat to see if it activates the furnace. The thermostat may be set too low. The thermostat should also be set on "heat." If you turn the thermostat up, and the system doesn't respond, the thermostat may be faulty.

Check the furnace's power supply. Even a gas furnace requires electricity to properly ignite. Verify the power switch is turned on. If it is, inspect the breakers to make sure they are all turned on, and check the operation lights on the furnace to verify that they light properly, indicating a good electrical connection. If the furnace consistently trips a breaker, it needs professional inspection.

Check the igniter. Spark ignition systems usually click several times when they're trying to light the furnace at startup, and you'll hear the noise if it works properly. A hot surface igniter should glow red as the furnace starts up. If it doesn't, the heating element may need to be replaced. Most furnaces also have an inducer fan that starts before furnace ignition. If it doesn't turn on, the fan motor may be faulty.

Clean or replace the furnace filter. A dirty filter blocks airflow, and this often leads to overheating. The furnace then shuts on and off in quick intervals known as short-cycling. Keeping the furnace clean and the filters fresh often eliminates this issue.

Verify that the furnace is getting gas. If you have a gas water heater, check the pilot to ensure that it is lit. If it is, the furnace should be getting gas, as well. If the water heater isn't working properly either, you likely have a gas problem, and an immediate call to the gas company is necessary. If your furnace has a pilot light that isn't lit, try lighting it in accordance with your user manual. Only attempt this if your furnace has a standing pilot light.

Turn on the indoor blower by turning the fan switch to the "on" position. It is usually on "auto." Some Goodman models may take up to 30 seconds to start the blower fan. If it doesn't turn on at all, and you know the furnace has power, the blower itself is likely faulty and needs to be replaced.

Inspect your heat exchanger for cracks. The constant heating and cooling causes expansion and contraction that eventually lead to damage. If you see cracks in the exchanger, it requires replacement.