Find out how your fridge and freezer works?
Here you will find out how your and most other fridges and freezers work. This article will help you understand what happens behind the covers.
Before we get started, lets make one thing clear. “We need to re-gas your fridge” or “Maybe my fridge needs gas” those are examples of lies with a very slight possibility of truth. Your fridge is not like your car – it doesn’t need to be re-gassed every 100 kilometres or a few weeks. If there is not enough gas in the fridge – there must be a reason why – probably a leak. If there is a leak, it is pointless to accept any work for any amount of money unless the technician can guarantee that he can fix that particular leak.
We will start behind the covers – most quality fridges these days will have an evaporator, defrost sensor, thermal fuse, defrost element, drain defrost element and a fan motor with a blade. All of this usually sits behind the covers or behind all your shelves.
99.9% of the fridges today also have a PC Board that controls all your components (including all of the above). So your PC Board will allow the compressor (also known as the motor) to push the refrigerant gas through the system and into the evaporator – evaporation occurs and cold is created. Extreme cold on top of cold, makes ice, your evaporator will get filled/covered with ice if the defrosting operation isn’t working as it should (where ever you see FROST FREE or NO FROST on a fridge, this type of fridge will have an automatic defrost system in place so it will do everything in the background without you have to manually defrost the fridge).
The fan motor pushes or pulls the cold air in order to circulate that cold air to get the whole cavity cold or frozen, in some cases the cold air is created in the freezer only and then pushed or pulled into the fridge cavity, whereby cooling the contents in your fridge. If the fan doesn’t run, it will not cool all of the contents of your fridge – in some cases, the more expensive fridges will have an evaporator in the freezer as well as the fridge. This means that your fridge now has two defrost systems in place and each evaporator and fan motor will run independently.
If your defrost sensor fails to report the correct temperature to your PC Board, the cooling experience will differ and, in most cases, the evaporator will get filled with ice as the PC Board will keep telling your compressor it needs more cold.
The same can be said for your defrost element – if the element is not working, your evaporator will fill with ice and your fridge/freezer will not be cold/frozen due to the fact there is no cold air circulating but only a frozen block of ice will sit in the mid or bottom section of your fridge/freezer whereby giving you the illusion that the freezer is still working well, when in fact it has the big block of ice, combined with the frozen foods to keep the cold temperature.
In most cases, your thermal fuse will prevent your your defrost element from working – thermal fuses are almost like your normal fuse. The only difference is that every fridge manufacturer will use thermal fuses with specific amperage and voltage parameters – they are usually enclosed and the wires are connected to a special kind of connector that plugs into the fridge/freezer – leading back to the PC Board. So if your thermal fuse is broken, electricity from the PC Board will not get to your Defrost Element and defronsting will not happen.
Some fridges have drain defrost elements – drain defrost elements are there to prevent the drain from freezing over. Your defrost function will melt ice off the evaporator and all that water needs to go somewhere. The melted ice will go down the drain, through a hose/pipe and into the drip tray which sits on your compressor. The water then evaporates over time from the heat of the compressor.
Your fridge / freezer can develop a leak in the pipes that carry the refrigerant gas and this will cause your fridge to gradually decrease in cold temperature and become warm inside in the end. The leaks develop, mostly, due to the poor quality materials used for the pipes carrying the gas. Your pipes will get very cold, then they will become warm, all the while condensation occurs and this happens several times a day. If the pipes are made of poor quality, they will develop leaks due to corrosion. If the leak is in a place where we can reach it, we will be able to repair/replace the pipes and get the fridge/freezer back into working order and if we cannot reach the affected pipes, unfortunately you can throw your fridge away. In some cases we can bypass the factory pipes and install an external condenser unit, like the one in the picture (the black grid sitting above the compressor).
In the case of some older fridges, you will find a compressor and a thermostat and in some cases a defrost element and defrost timer. The thermostat will run the show – but when the fridge reaches the set temperature, the thermostat will switch the compressor off and give power to the defrost timer which will in turn give power to the element for a specific time period. The that time has elapsed, the defrost timer will switch the power off to the element and send a signal to the thermostat saying that defrosting is done. The thermostat will then give power again to your compressor and so the cycle begins again.
To the right you will find a picture of a common mechanical thermostat and domestic compressor.
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Please note that our callout fee has increased from R420.00 to R500.00 – effective 01.04.2020
The callout fee is compulsory and does not go toward the repair if the quote is accepted