Automatic Temperature Control - Maytag NAV2330 Service Manual

Automatic Temperature Control

To avoid risk of electrical shock, personal injury, or death, disconnect power to washer before servicing, unless
testing requires it.
ETC Control Operation
ETC Cold Fill- The ETC cold fill toggles the water valve hot supply on and off to maintain a cold wash temperature
of approximately 55 to 65° F. If the cold water output is above 55°F, the ETC Control Board will not
energize. As a result ETC will not affect the water fill process in the cold wash setting.
ETC Warm Fill- The ETC warm fill toggles the water valve hot supply on and off to maintain a warm wash
temperature of approximately 69° to 79° F. If the cold water output is above 69° F, the ETC Control
Board will not energize. As a result ETC will not affect the water fill process in the warm wash
setting.
ETC Hot Fill- The ETC hot fill toggles the water valve hot supply on and off to maintain a hot wash temperature of
approximately 81° to 91° F. If the cold water output is above 81° F, the ETC Control Board will not energize. As a
result ETC will not affect the water fill process in the warm wash setting.
ETC Control Diagnosis
The cold water valve is energized continually during fill. 120 VAC is supplied from pin #1 on the ATC board to
energize the hot water valve as needed to achieve the desired temperature. In most instances, the hot water valve
will only be energized for a short time. 120 VAC is supplied to the ATC board at pins 8 and 9. A thermistor is used to
sense the water temperature entering the tub. The thermistor resistance is approximately 1100 ohms at room
temperature (70 °F). The ohm reading will increases as the thermistor temperature rises. Because the resistance is
higher, the voltage is lower coming out of the thermistor and into pin #2 on the ETC board. The ETC board monitors
pin #2 to determine the correct water temperature.
The water temperature switch input setting is monitored at the ETC board and can be diagnosed by checking the
following:
Hot Selected – 0 VAC at pins 3 to neutral and 4 to neutral.
Warm Selected – 120 VAC at pin #4, 0 VAC at pin #3.
Cold Selected – 120 VAC at pins #3 and #4.
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WARNING
Pin #1
16022937 Rev. 0 13