Why is there ice build-up in a frost-free cooler?

temp too cold and door seal not effective are 2 reason for this
48 F is too cold for wines (8.8 C) and continually opening and closing of the door allows humidity into the cabinet that results in frost and ice

Anytime there is ice buildup it will not cool. Was the door left open? If so that would cause ice buildup. If it wasn't left open and it is a frost free model you have a problem with the defrost circuit. Unplug it and Manually defrost it with items removed by using a hairdryer and towels to absorb water from defrosting Afterwards it will cool again .If the defrost circuit needs service the unit will continue to frost up. Usually in frost free models there is a heater that goes bad.

Some dual temperature wine coolers build up frost in the rear and top of the main compartment. Check the defrost timer, located either inside the main compartment near the light, or outside on the back of the wine cooler near the compressor. Look in the owner's manual for the correct settings for the defrost timer and adjust yours as needed. Make sure that you have the wine cooler in a spot where the outside temperature remains at or near room temperature to reduce frost buildup.

check the door seal, make sure that its not ripped or dirty. Its possible that moisture is entering the wine cooler thru the door gasket. Frost is normally the result of warm moisture mixing with cold air. The door gasket should be the problem. if you thoroughly examine and its fine, let me know and we'll go to the next step.

the noise is quite possibly the freezer fan cutting ice behind the wall
you may have an issue with your defrost system

Shut down your refrigerator and unplug it for a few minutes - plug it back in and turn back on to see if it resets your control board - if problem persists you may have to get it serviced and have them check the control board, evap fan and defrost timer. there should be no frost build up in your freezer, if your unit is a frost free, auto defrost, it should go through a defrost cycle. maybe your evap fan is plugged up with ice buildup or if your evap fan is working properly, a control board issue.

If noise stops when you open the door, you may have a noisy fan (or could have ice build up, causing fan blade to hit ice and cause noise). I gather it is a frost-free model ie has a fan in the freezer compartment. If noise is caused by fan hitting ice build up, you may have a problem with the auto defrost system, as you should not get ice build up in a frost free.
Noise stops when you open door because fan turns off when door is opened.

Since this model is frost free and u are finding ice in the bottom back the problem may be due to either or both of these:

• Low refrigerant coolant gas(freon/CF4)
• The fan & heater *** blower assembly could have malfunctioned. To check put ur hand near the outlet of the bower outlet to feel if the fan is operational.

This may be the first things to check and post ur reply as comment for us to help find the exact problem..........................sodeep

The fan should blow air into the heat sink. The warm air exits the heat sink at both ends. (It might work the other way, haven't tried it.)

When you have ice in your cooler, you know the thermo-electric element is working well--it's below freezing!

Ice builds up because there is water in the cooler. For example, in humid weather, you open the cooler, some humid air gets in, and the cooler temperature condenses the water. You have to empty this water, either by tipping the cooler, or using a sponge.

You can easily defrost the cooler by unplugging it for an hour or so. You know it's time to defrost when you hear the fan blades making a racket because they're hitting something--a thick buildup of ice.

take back panel off freezer and check for ice build up which will block air flow and temps will rise. melt off carefully with a hairdryer.make sure drain is also clear and use hot water and patience if blocked with ice. if fault re-occurs, you have a fault with defrost system