Why is my fridge not cooling properly?

Question

I live in a rental apartment, and it came with a poor quality fridge. It's your standard plastic box with a cold plate around 1/4 of the way down. The upper part is the "freezer" and the lower is the regular fridge. There is little to no insulation, all the freezer part does is gather ice and can't even keep an ice cream from melting.

Anyways, today the ice started melting for no apparent reason. The temperature slider is in the same place (max). I can't see what's going on with the cold plate since there is still a solid couple of inches of ice around it. The engine is still making the same old sound. Its melting at like 2 drips per second? I've gotten around half a gallon of water out of it over the day.

I've put a towel under it to collect the water, I don't really care for the well being of the fridge, I'm more concerned with why its suddenly being worse than usual. Could the ice have cracked the cold plate or something? Would the fluids from the cold plate be dangerous?

EDIT: thank you to all answering, there has been a development:

I started defrosting the fridge a little while before posting the thread. Couple of minutes ago, the bottom half of the ice that was stuck to the plate just fell off and into the plastic thingy below it which also fell to to the bottom of the fridge. Nothing broken there, the plastic is just naturally flimsy.

Now that I can see the plate, it appears to be tilted (I'm assuming its supposed to be horizontal) by around half an inch. Shortly after that, I could hear some more dripping except this time it came from somewhere I couldn't see and made this kind of boiling noise, I'm assuming that would be the coolant. I don't know if that's normal since it only lasted a few minutes, could be a heat adjustment thing, its completely silent now.

EDIT2: I tried turning it on again, the engine started up for a few seconds but then stopped. I can also kinda smell it now, a faint smell thats somewhat like the window cleaner fluid in cars. My theory is that the weight of the ice must have been enough to bend the pipes holding the plate (they are literally the only thing) and that they broke.

EDIT3: I finally got the fridge out of its hole (it fits exactly inside one of the counters) and got a look at the backside. One of the pipes leading from the compressor to the inside of the fridge is almost 100% rust at the point where it goes through the back wall. I'm guessing since that was the cold pipe and the radiator bit was right next to it, it was a good place for condensation to form. It has a big gash in the middle (like a good centimeter), frankly I'm surprised its worked so far at all.

Answer 1

It is very unlikely that the ice cracked the cold plate, because the ice builds up from the plate surface outward as water condenses on it and freezes. In order to generate any force on the plate you would need to start with a volume of liquid water which could freeze and expand. There is no place on the plate that would hold a puddle of water big enough to do this.

I can imagine a scenario involving melting, refreezing, and trapped water that could theoretically put pressure on the plate but it seems about as likely as a small meteorite crashing into the fridge. Which come to think of it sounds like the best thing that could happen to it.

Really, the only way a cold plate or freezer coil ever gets physically damaged is by the user attempting to physically remove the ice buildup with a pointy tool.

If the cold plate did spring a leak, the particular dangers depend on the type of refrigerant, but practically speaking, you are not likely to be badly harmed by a leaking home refrigerator, no matter how cheap it is.

Quote from a worksafe site http://www2.worksafebc.com/i/posters/2013/ws_13_10.html:

"Some refrigerants, such as ammonia, are very toxic. They are defined as toxic process gases under Part 6 of the Occupational Health and Safety Regulation. Other refrigerants, known under the trade name Freon, are non-toxic. These include refrigerants such as R-22 and R-410A."

The good news is: your fridge is noisy so it must have a compressor, so it probably uses R-410A instead of ammonia. The bad news is: your fridge is noisy so it is probably about to become TU very soon.

If your fridge leaked at the cold plate, and if the refrigerant was toxic, and if some of the toxic refrigerant was trapped in the ice buildup, the ice might become toxic. You don't need to worry about this because since (a) R-410A is not toxic, and (b) you are not stupid enough to eat the ice buildup from a cheap refrigerator.

To answer the question you didn't quite ask, the thing is likely just completely worn out.

If the box has been slowly getting warmer then ice buildup could be the cause. You could try unplugging it and letting the ice melt (takes maybe 12 hours) and then plugging it in again to see if the cold plate even gets cold anymore.

But if the failure to cool was sudden, then the plumbing has sprung a leak or the compressor has packed in. Or both. What often happens to a refrigerator is this. The circulating fluid contains not only refrigerant but also lubricant for the compressor. A slow leak reduces the pressure in the system until very little heat is pumped, and very little fluid is circulated. The compressor is forced to work longer and harder with less lubrication and eventually burns out its seals or just breaks.

My rule for deciding to fix or discard is this. If the failure was characterized by a long slow decline followed by a complete failure, junk the fridge and replace it. If it failed suddenly without warning, turn it off so it doesn't tear itself up. then try to fix it.

Answer 2

The sensor that tells the compressor to run is probably coated with ice or frost.When this happens the compressor wont turn on enough because the probe is still frozen, look for a small metal tube like a wire about 1/8" thick usually clipped close to the cooling plate. this needs to stay free of ice for the fridge to maintain temperature. don't use an Ice pick to chip the ice off because you may damage the evaporator coils and release the freon. It is best to turn the fridge off and let it melt, (food in a Ice chest) I have used warm water to melt the ice faster but this makes a mess also. I don't recommend hair dryers as there could be a shock hazzard with all the water. Hand held torches may damage the coils and plastic parts. Usually a bad seal on the door causes the excessive buildup.

Answer 3

Does your mini fridge have a manual defrost button? It is usually near the thermostat control, may be labeled or just a red button. The manual defrost on simple fridges just turns off the cold for a while to let any ice buildup melt. You may have pushed the button by accident.

Incidentally, the fridge and the freezer will both perform best if there is little or no ice around the cold plate. The ice actually insulates the rest of the fridge and freezer section. If you notice ice building up you should try to get rid of it, either by using the aforementioned manual defrost mode or just unplugging the fridge for a few hours until the ice can be removed. (Do not try to pry the ice out, you risk damaging the coolant lines.)