A.O. Smith GAHH-40 Control Display Troubleshooting, Control Display Status Problem Solution

CONTROL DISPLAY TROUBLESHOOTING

ELECTRONIC CONTROL DISPLAY

Please check guidelines below. For your safety, water heater service should be performed only by a qualified service person.

Read the GENERAL SAFETY INFORMATION supplied by the water heater manufacturer.

	CONTROL DISPLAY STATUS	PROBLEM		SOLUTION
1.	“POWER” Flashing		1.	Check the 5-conductor data cable that
		Communication Error		runs between the upper and lower
		The system has detected a		controls. Check that the wiring is not
				broken, and the connectors on both ends
		communication error between the
				are properly seated in the mating
		upper and lower controls.
				connectors.
			2.	Replace the upper control, if the problem
				persists:
			3.	Replace the lower control.
2.	“HEATING” and “SHORT” Flashing		1.	Turn the power off for 10 to 20 seconds
		The self-diagnostic tests have		then on again to clear the error code.
		found a problem with an internal	2.	If the error code persists or cannot be
		circuit.
				cleared, replace the lower control.
3.	“HEATING” and “OPEN” Flashing		1.	Gas supply is turned off – pressure too
		Ignition/flame failure.		low. Ensure supply and manifold gas
		The water heater has reached the		pressures are within requirements in the
				installation manual. Manifold gas
		maximum number of retries and is
				pressure is non-adjustable, if pressure is
		currently locked out for one hour.
				off by more than 0.3” W.C. (75 Pa)
		Cycle the power to the water		replace the lower control.
		heater off and on to reset.	2.	Low supply voltage – should be 115 –
				125 VAC.
			3.	Ensure flame sensor is making good
				contact with the burner flame, ensure
				flame is steady.
			4.	Ensure the flame sensor is clean – use
				ultra fine steel wool or Scotch-BriteTMpad
				to clean the flame sensor.
			5.	Ensure the hot surface ignitor is
				positioned to provide consistent ignition.
			6.	Check for any cracks in the ignitor
				assembly ceramic insulators – replace
				ignitor assembly if damaged.
			7.	Check resistance of the ignitor at room
				temperature (77°F – 25°C) at the plug
				end. Replace ignitor if the resistance is
				not within 1.38 to 2.31 ohms at room
				temperature.
4.	“HEATING”, “OPEN”, and “SHORT” Flashing		1.	Ensure flame sensor is making good
		Weak flame sensor current.		contact with the burner flame, ensure
				flame is steady.
			2.	Ensure the flame sensor is clean – use
				ultra fine steel wool or Scotch-BriteTMpad
				to clean the flame sensor.
5.	“ECO” and “OPEN” Flashing		1.	Turn the power off for 10 – 20 seconds
		Water temperature in the tank has		then on again to clear this error code.
		exceeded 185°F (85°C) and has	2.	Replace the lower control if the error
		activated the ECO.
				code persists.

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