Fridge And Freezer Compressors
The compressor in your fridge, freezer or fridge freezer is probably the most important part of the unit as it is the heart of the machine, the motor that drives the refrigerant gas around the system causing the cooling to happen.
Most people just see it as the “black bottle thingy” at the back of the unit with a few pipes coming off it and some wiring.
Obviously, it’s a bit more than that.
What Compressors Do
Whilst many people get all confused by how fridge and freezers work they are in fact pretty simple things relying on technologies that are ancient in many ways, the notion of how a modern fridge works have been with us for a long, long time.
That is to say that the gas in the system is “pumped” around the pipework by the compressor and that is more or less what it is, a pump.
This small electric pump is housed in a sealed chamber, suspended in oil with a whole bunch of bits and bobs that most people will neither need to know about or indeed care about. So long as it works.
This way of refrigerating stuff goes back many decades, it’s not new at all and is incredibly well understood and ubiquitous in the domestic appliance industry.
The only real change in the past fifty years or so has been in the reduction of energy use by using the likes of what they call “linear compressors”, all that means is that instead of being a single speed full on and full off, a linear compressor can ramp up and down much like a dimmer switch if you will so, it doesn’t need to draw full power.
The downside or, some see it that way, of linear compressors, is that they require additional electronics to control them and all too often electronic sensors in the unit as well for more accurate control to get the energy use down.
Many manufacturers will drone on about how they use advanced technologies and all that nonsense when really, they’re all much the same whether they go on about inverter technology or whatever they call it, the same thing in the end.
The future may hold magnetic refrigeration, maybe, but we’re quite a way from that being an affordable alternative in domestic units.
Wear And Tear
So here’s the thing about compressors, they will eventually all wear out.
Sorry but it’s true, they do not last forever and will ultimately fail in one of three ways.
- They burn out or short electrically
- The internal seals wear out
- They seize up
For the most part in the real world, that’s about it really as there are not too many ways such a simple technology can break.
It is either the only moving part in any refrigeration product or, one of the few and as it is a moving part, it will wear out for sure at some point. Some last longer than others and when you talk to fridge guys they will almost all say that Danfoss, EMBRACO and maybe one or two others are good pots as we call them, the rest and especially the Asian ones, not so much.
In the first few years of life, assuming that the unit is installed correctly, has good airflow and so on then, the most common thing to happen will be an electrical failure. You can see other problems appearing but it’s not so common.
Normally when the compressor fails electrically it will just die, the unit will be dead and will not cool down at all.
Very often you will get the “click - buzz” sound of death from the relay trying to fire up the compressor with no success.
With the technologies being so well understood and honed, whilst failures do occur and more so on will we say, less high-quality items from not so well known manufacturers, compressors will normally pop for a reason. The most common of which is where the machine is installed or how it is installed that will be the issue that in turn causes the premature failure of the compressor.
After many years normally the seals inside the compressor can wear down or just fail and this means it doesn’t pump so well.
You start to see poor cooling or no cooling at all if the oil gets dragged from the compressor into the system and that will cause a system choke.
Prior to this, you’ll usually see a deterioration in cooling performance or extended runtimes as the compressor struggles and works overtime to try to cool the unit. Of course, that can cause it to overheat and seize or just burn it out.
If this happens normally the compressor will just stop running and once again you will get the “click - buzz” of death as the relay clicks away trying to start the unit.
This can happen early in life but it’s not that common and often as a result (again) of installation or airflow issues.
Replacing A Compressor
This is a specialised repair and you cannot replace a compressor on a DIY basis.
There are two ways to go about it, you can either braze a compressor which most fridge guys will do as they almost universally will tell you that’s the most reliable way or, you can use a compression system known as Lokring that many now use.
The reason they use Lokring is that you are not brazing in a customer’s home so, less risk with fire and all that sort of stuff. Even although it costs more to do in respect to materials and in many repairer’s eyes is less efficient.
Oh, and the new gas being used in domestic systems is R600a, Iso-Butane so that’s sort of highly flammable and having naked high heat flame near that if you don’t know exactly what you’re doing can end badly. In order to avoid people that are not perhaps as skilled from blowing up themselves or a customer’s home, they use Lokring.
Health and safety at work gotta love it. Or is that, not enough skilled people?
After you get through all that you then have to recharge the system with gas, the exact amount of gas or it will not cool as it should or, cool too much. The charge has to be precisely weighed, the system then sealed once more.
As you can no doubt understand all of this needs very specialised (expensive!) tools and kit to do so you cannot replace a compressor yourself, you need a professional to do it for you.