Maytag Built-in Refrigeration, Manual

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cascade down over the contents. This constant airflow provides temperature control in all
areas of the cabinet within one degree of the setpoint.
When there is a call for cooling in the fresh food section, the fresh food damper will open
and allow cooler air to be drawn from the freezer compartment. The compressor may not
energize at this point if sufficient cooling can be accomplished with the existing air in the
freezer compartment. When the thermistor has been satisfied, the damper will close. The
fresh food stirrer fan will continue to be energized whenever the fresh food door is
closed.
The circulation fan in the freezer compartment is also a DC variable speed fan controlled
by the Main Control board. This fan will energize whenever the freezer door is closed
and there is a call for cooling from the Main Control board.
Servicer’s Note
The circulation fans and dampers can be operated independently of each other with the
service mode. This operation does not rely on the doors being closed or the current
cooling demands on the system. Service test 07 will check the operation of the fresh food
fan and Service Test 19 will report the speed of the fan in revolutions per second (RPS).
The evaporator fan can be checked with service test 08 and the speed reported through
service test 20.
The fresh food damper can be cycled to an open state using Service Test 09 and closed
using Service Test 10.
Since these are DC supplied variable speed motors, they cannot be tested using a jumper
or cheater cord. Applying 120VAC to the inputs of these components will damage them.
Verify proper power to the component and if the motor is not operating, replace the
motor.
The fan blades must be properly installed and oriented for optimum airflow. Seat the
blade for placement in the fan shroud openings.
Defrost System
The defrost system is both adaptive and preemptive.
The adaptive portion of the system adjusts the run time between defrost cycles to provide
the optimum defrost duration.
Preemptive defrost will attempt to prevent defrost cycles from occurring during high-use
periods.
The Main control board monitors door openings to track high usage periods. If the system
identifies that a defrost cycle is likely to occur during a high use period, it will either
begin defrost early or delay defrost until after the high use period.
Before initiating a defrost cycle, the system will operate at maximum cooling capacity for
30 minutes. This will sub-cool the freezer section and result in a freezer temperature up to
ten degrees below normal. This additional cooling will help to prevent the interior
temperatures from rising much beyond the setpoint temperature during defrost.