Goodman Gas-Fired Warm Air Furnace GKS90904CX

Turn OFF the electrical power to the furnace.

Turn OFF the gas supply to the furnace.

Disconnect the gas line from the furnace.

Remove the burner/manifold assembly by unscrewing it from the partition panel.

Disconnect the flue pipe system from the induced draft blower.

Remove the induced draft blower.

Remove the drain and pressure tap hoses from the recuperator coil front cover.

Turn OFF electrical power to furnace

Remove filter(s) from the following locations

Replace filter(s) by reversing the procedure for removal

Turn ON electrical power to furnace

Was the filter replaced with the same type and size?

Check the flue pipe system for the following issues

Inspect the outside termination and connections at and internal to the furnace

Check the heat exchanger for the following issues

Turn on the furnace at the thermostat

Allow several minutes for flames to stabilize

Are the flames stable, quiet, soft, and blue?

Do the flames extend directly outward from the burners without curling, floating, or lifting off?

Are there any yellow tips on the flames?

Do the flames impinge on the sides of the heat exchanger firing tubes?