We had a similar odd sound from the back of our refrigerator.
There's a few different parts back there that can make noise: The compressor, condenser fans, and defrost timer. Apparently the fans can be cleaned fairly easily, and the timer can be replaced if its electric motor starts making noise.
In my case, we called in an independent service technician (found via Service Magic). He diagnosed the problem for us at no charge. Unfortunately for us it was the compressor, and a new unit would cost almost as much as a new fridge, so we ended up getting a new fridge.
But in your case, maybe you're lucky and it's one of the other parts.
Freezers aren't really designed to freeze things, they're designed to keep things frozen. To change one pound of 32°F ice to 31°F ice, requires the removal of .5 BTUs. To change one pound of 32°F water, to 32°F ice, requires 144 BTUs. Therefore, it requires far less energy to keep an item frozen, than it does to freeze the item in the first place.
Almost all sources (including the USDA) agree that a freezer should be kept at 0°F (-18°C), to store frozen foods. Though a temperature of -5 to -10, is recommended to freeze food.
If the back panel of the freezer is popping off, you might want to investigate what is causing it to pop off. If there is ice forming that is causing the panel to pop off, it could mean that the refrigerant in the system is low, and there may be a leak. This is probably a unlikely scenario, though it is possible.
The more likely cause, is poor air flow.
If there's not good air flow through the condenser, the heat removed from the refrigerated compartments will not be removed from the refrigerant. At the same time, if the air flow through the evaporator is poor, heat will not be removed from the refrigerated compartments effectively. Maintaining good air flow within the refrigerated compartments is also important. The cooled air needs to move throughout the compartment, so heat can be taken away.
- Make sure the condenser fan is working, and there's not a lot of dust and debris obstructing the flow of air across the condenser.
- Make sure there's good air flow across the evaporator, and that the evaporator is not icing over (this may require disassembly of part of the refrigerator).
- Make sure there's good air flow within the freezer, and that items are not blocking the vents.
Best Answer
A large clunking sound could be many things, Since Refridgeration equipment is a licensed trade we can look at a few things. But with the available information it is hard to provide a proper answer. Two long for a comment so here are a few things to check.
Blew out the coils, is the fan clean and functional if it has one.
With out a proper air flow on the condensing coils the heat exchange is limited. I ask about the fan because it can be the sound hitting something or clunking Next I would look in the freezer section is it a frost free model? Again is the fan working, coils iced up? Usually with frost free you have to remove covers or defrost if it works for a while after defrosting it could be the fan or the defrost timer/ heater to thaw the coils. If the above all check out we are to a pressure check. Most refrigerators do not have a service port so one has to be added to check the charge and if needed recharge the system.. there are mechanical port / valves that can be added for under 20$ but these are questionable in my opinion but may be an option for a less expensive repair if the system just needs a recharge.