A.O. Smith GAHH-50, GAHH-40, 315456-002 Control Display Status Problem Solution

cont.

	CONTROL DISPLAY STATUS	PROBLEM		SOLUTION
6.	“P-SW”, “OPEN”, and “CLEAN SCREEN” Flashing		1.	Clean the screen on the combustion air
		The air pressure switch contacts		intake tube. Retest, if the problem
		remain open longer than 5		persists:
		seconds after the combustion fan	2.	Ensure the pressure switch sensing tube
		is energized.
				is in good condition and securely
				connected at both ends.
			3.	Ensure the inner door to the combustion
				chamber is secure and the gasket is
				properly sealing.
			4.	Take a pressure reading from the
				pressure switch’s sensing point on the
				inner door with a digital manometer.
				A. If actual pressure reaches design
				“make-point” for the switch check
				pressure switch contacts continuity
				with the combustion fan running. If
				switch contacts remain open replace
				switch.
				B. If pressure does not reach “make-
				point” check system for restrictions
				and cleanliness.
7.	“P-SW” and “SHORT” Flashing	The air pressure switch contacts	1.	Turn off power to the water hater.
			2.	Locate the pressure switch wiring –
		remain closed for more than 5
				ensure pressure switch wiring is correct
		seconds when they should be
				and not jumped.
		open.
			3.	Remove wires to both terminals on
				pressure switch.
			4.	Check pressure switch contacts with an
				ohmmeter for continuity.
				A. If pressure switch contacts show
				continuity (closed circuit) replace
				the pressure switch.
				B. If pressure switch contacts show
				open circuit and all wiring is correct
				– replace the lower control.
8.	“IGN” Flashing	Open ignitor circuit	1.	Check all wiring to the hot surface ignitor.
			2.	Check the 3 pin Molex ignitor assembly
				plug and receptacle on the lower control
				for a good connection. Repair or replace
				parts if necessary.
			3.	Check resistance of the ignitor with an
				ohmmeter on the ignitor assembly plug.
				Replace ignitor if resistance is not within
				1.38 and 2.31 ohms.
			4.	If above checks are good – turn off
				power for 10 seconds and then back on.
				If this error code will not clear and the
				ignitor resistance is within specifications
				– replace the lower control.
9.	“FV-SENSE” Flashing	Flammable Vapor Sensor has	1.	Contact a service agency to determine
		detected the presence of		the cause.
		flammable vapors and is in lockout
10.	“LDO-SW”, “OPEN”, and “CLEAN SCREEN”	The air pressure switch contacts	1.	Clean the screen on the combustion air
	Flashing	remain open longer than 5		intake tube. Retest, if the problem
		seconds after the combustion fan		persists:
		is energized.

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