If it's making this noise the whole time it's running, listen to see if the noise is from under the unit or inside. If it's from underneath, the noise could be from the compressor, the condenser motor or it may be a vibration noise. In this case, you will need to pull the unit out far enough get behind it and remove the back panel. Now you can determine if the compressor is noisy, if itâ€™s from the motor or if it's a vibration. If it's in the compressor, there is no fix except to replace the compressor. If itâ€™s from the motor, try adjusting it and if it doesnâ€™t help, the motor will need to be replaced. If it's a vibration, check the condenser and refrigerant lines to try and stop it.
If the noise is from the inside, it will probably be from the fan motor. In this case, the motor will probably need to be replaced. For more specific information about your refrigerator, please resubmit your question, with a complete model number and any additional details.