Hello, this is sounding like a defrost issue but it could be something else. The problem why it is not cooling very well is because the evaporator is covered in ice and is blocking the flow of air to the evaporator. Hence, poor performance.
Ice build up is sometimes caused by door being left ajar, moisture on improper food packaging in the freezer, or a defrost issue, Meaning, the automatic defrost cycle is not happening. Let us first defrost your unit so that it will cool down right away.
If there are not much food in the freezer, I would like you to unplug it for 8 hours, leave the freezer door open, put a desk fan on front to accelerate defrosting . Then plug it back and observe . The unit will cool down but still, observe it for the next couple of days if the problem would comeback. If it does, then you have a defrost issue .
Thank you for using JustAnswer.
Please stay safe.
Please do not forget to click ”Finish conversation with expert” . Thanks
Please ignore the phone service offer..…It is not me who initiate it but the site…but if you really want a phone call…please let me know. I only do phone call for USA customers but viber, FB messenger, or FaceTime for customers outside of USA. Thanks.