Modern or high end fridge freezer units often use fans some for circulation of the cold air from the freezer cavity to other cavities such as the fridge. There may also be cooling fans on a compact condenser as well to aid cooling of the refrigerant.
Fans will have motors to drive them on modern newer fridge freezers the motors are usually DC motors older fridge freezers used mainly AC motors so understanding both is a must when it comes to testing and fault finding.
AC motor generally used are shaded pole types which are usually very reliable , they are self starting, single phase induction motors. you can measure the windings of these to ensure they are intact otherwise it could be a bearing or the mechanical side of the fan that is at fault like a blockage or frozen solid . resistance reading are usually 800-900 ohms or thereabouts.
DC motors are usually BLDC brushless motors these need a speed sensor usually a hall effect sensor to now where in the rotation the rotor is so timing of rotating magnetic field can be controlled. The control is usually done buy a electronic motor drive board where speed and rotation can be controlled. Again these can be subject to mechanical fault and freezing solid , you can ohm test the coil windings and the sensors but its hard to locate and test the motor drive PCB.
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