Hi!!
The easiest way to find out if the evaporator fan is working is to leave the Freezer Door open for a couple of minutes, when the compressor kicks in, the evaporator fan must also kick in. Make sure it comes on strong blowing plenty of cool air. Note that the fan can come in some times and fail other. If you suspect the fan is not operating properly replace it, it is rather common for a fan to fail after a few years of use, replacing the fan motor is part of preventive maintenance. If the fan is failing, the evaporator will get covered with ice a few minutes after the compressor starts working, since the defrost timer activates the defrost every six to eight hours, it may seem that it is not working.
You can get a replacement fan motor at any appliance parts store, take your motor to make sure to get the right replacement, the blades are to be removed and reinstalled on the new motor.
Click on the following link for an exploded view of the freezer,
http://www.searspartsdirect.com/partsdirect/partsdirect/showSubComp.pd?imageUrl=http://c.searspartsdirect.com/lis_png/PLDM/G0201124-00003.png to remove the evaporator fan, Unplug unit from wall outlet, remove fastening screws on the back of the freezer cover, remove back cover just enough to unplug electrical connector and mounting screws, remove fan assembly. If the unit is equipped with ice maker, disconnect electrical connector to Ice Maker, remove fastening screws and remove unit.
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