Fixing a faulty ice maker

Almost all these little countertop ice makers look virtually identical inside. It makes me wonder if they originate from the same factory, or if it's just copied by many different factories. These units are an extremely good example of a well-evolved and efficient design with minimum component count.

They also inevitably have the same technical issues, and fortunately it's rare that the refrigeration system or control PCB are the problem. That makes them fairly easy to repair yourself, once you've worked out how the cover comes off. Sometimes it's from the base and sometimes from the top like this one.

As always, ensure you don't finger the insides while power is applied, or leave it running with the cover off when other people may be present. Also keep in mind that the 12V supply may not be SELV (separated/safety extra low voltage) but may be FELV (functional extra low voltage) if the circuitry references it to the mains supply for economy or to directly drive things like mains voltage components.

The main faults that occur with these units are:-

The scoop motor jamming up due to moisture causing corrosion on its main bearing.
The scoop's end of travel limit switches corroding and jamming.
The water sensor getting scaled up and not detecting water flow.
The water pump jamming due to ingress of dirt or hair.
The condenser fan failing and causing poor ice making performance.
The infrared emitter/sensor failing due to water ingress - usually the clear emitter.
A dirty condenser coil due to pet hair or excessive dust resulting in poor ice making.
Condensation or corrosion in the control button panel resulting in unresponsive switches.

All these things are generally fixable by either cleaning or replacing components.

Quick summary of how refrigeration works. Imagine a compressor with a loop of pipe going from its output to its input, and a restriction in the middle of that pipe that limits liquid flow.
The compressor compresses the gaseous refrigerant, and it condenses into vapour under pressure, giving off heat in the process. That vapour condenses into liquid in the pipe and then squeezes its way through the mid-pipe restriction to the vacuum side of the compressor. As it enters the side of the pipe with a vacuum it changes from liquid to gas, and absorbs heat in the process. Then the cycle repeats.

The hot gas defrost that rapidly drops the ice cubes, bypasses the condenser and its long thin capillary tube (the mid-pipe restriction) and diverts the hot vapour directly through the ice forming evaporator prongs briefly.

The styrofoam insulation in the ice trough does a surprisingly good job of keeping the ice from melting too fast. There's still ice in the trough after 8 hours when the unit is not running. Any ice that does melt goes straight back into the water reservoir for reuse.


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