Coleman Furnace Error Codes: DGAA and DGAH Flash Guide

Record complete flash groups through the port

Johnson Controls says the numbered pattern uses one second on and one second off for each flash, with a two-second off period separating code groups. Take a video long enough to capture the repeating group rather than counting one isolated blink.

For the following numbered entries, its printed page 8 gives these meanings. Keep them scoped to this manual and the control fitted to your furnace.

Do not switch power off merely to make the indicator disappear before recording it. That is a diagnostic step, not permission to leave an unsafe furnace running. The safety instructions above always take priority.

Keep the listed causes as possibilities

For two flashes, Johnson Controls says the pressure-switch contacts were closed when the control checked for an open condition at the start of a heating cycle. Its listed possibilities are a faulty pressure switch or miswiring.

For three flashes, the expected closure did not occur. The manual names a faulty inducer, blocked vent, broken pressure-switch hose or faulty switch as possible causes. The number alone does not select which component needs replacing.

From a safe ground-level position, note visible vent damage or obstruction for the technician. Do not climb onto the roof, disconnect tubing, open the vent or bridge switch terminals to obtain heat. Johnson Controls explicitly prohibits pressure-switch bypassing and adjustment.

Give service the flash group and whether the inducer appeared to start. If you cannot tell from outside the closed cabinet, record that uncertainty. Leave measurements and combustion-system inspection to the qualified person.

Look at the accessible airflow path

Johnson Controls says four flashes means a primary or auxiliary limit opened. It lists a dirty filter, improperly sized ducts, incorrect blower speed, incorrect firing rate or a faulty blower motor as possible causes.

The same code description says the supply-air blower and inducer operate during this fault. A running blower therefore does not establish that the furnace is heating normally or that a limit can safely be reset.

Check accessible return grilles for objects blocking them and note closed supply registers. The manual’s owner troubleshooting checklist calls for clean filters, unobstructed returns and open registers. Report known filter condition or overdue maintenance without opening the furnace here.

Do not change blower-speed wiring, gas settings or an internal limit. Johnson Controls requires qualified cleaning of furnace surfaces and components. A return grille cleared from outside is useful information, but it does not confirm the whole cause of a limit trip.

Use the matching label when the manual is unclear

Johnson Controls defines five flashes as gas flow with no call for heat and directs checks of the gas valve and its wiring. Do not force another heat call or keep restarting it. Arrange prompt qualified assessment, using the overheating or gas-shutoff safety instruction if that condition is present.

The same page’s code list labels steady on as normal operation. However, its preceding prose also associates a continuously lit indicator with control replacement. Those statements conflict; do not condemn a board from a steady light alone. Use the fitted control’s label and qualified diagnosis for a no-heat complaint.

The page mentions numbered sequences one through six but supplies no separate six-flash definition. Do not import one from another Coleman family. Record six flashes, confirm the model and control revision, and have service identify its applicable chart.

Johnson Controls also describes a 60-minute automatic lockout reset for specified conditions. That is control behavior, not an owner instruction to cycle power or wait through repeated unsafe operation. It does not remove the requirement to resolve an ignition, airflow or gas-control fault.