The cooling process
I'm going to explain it in a simplistic way so hopefully anyone can urderstand. Starting with the compressor; this is the part that moves the freon through the system. Based on the fact that you cannot compress a liquid, the freon has to be in a vaporized state when it is pushed through the compressor. so at the begining of the cycle we have a high pressure vapor, on the outlet end of the compressor.
Keep in mind that freon usually boils at a negative temperature, so it is very easy to get it to boil under these curcumstances.
After the compressor comes the condenser where high pressure, vaporized freon is turned into a liquid through a cooling process. The freon can be cooled by two popular methods, one is an air cooled condenser (which simply has a fan blowing across the coils,) and the other way is by chilled water. Chill water is a little more complex and for most cases you home refer unit will be air cooled, so I won't get too deep into water cooling.
Usually attached (or next to) the condenser is a receiver which is a small tank where the liquid freon sits.
Next in line is the Thermal expansion valve (TXV), which is somewhat complex. this component is equalized by three different pressure sources.
First is pressure which comes from the sensing bulb which is attached onto the outlet end of the Evaporator,
Second is evaporator inlet pressure,
Last is the set spring tension.
If your refrigeration unit has a TXV you can adjust the amount of Freon that passes through the system by increasing or decreasing spring tension. (it usually has a small nut that can be adjusted with a flathead screwdriver.)
An important note for those of you who are thinking of making TXV adjustments; Adjusting the TXV should be a last resort and in most cases it shouldn't even be touched unless it looks rusted, or broken. When all else fails remember this advice Just don't do it!!!!!!!
Chances are that the manufacturer installed the TXV in a preset condition, and if you mess with it, it could throw the entire system out of sync, and it would be very difficult to get it running properly afterwards.
If you do decide to make an adjustment on the TXV always remember what direction you made the adjustment and how many turns you made. You need a lot of patience when doing this so my advice is to make very minor adjustments at a time and then wait a few hours to see how the system reacts.
This is the part where heat is removed from the inside of the refrigerator or freezer. what's happening here is the process of heat removal. Let's say for instance that you put a chunk of meat in the box and it puts off heat. That heat is usually blown by a fan over to the Evaporator coils, those coils have some liquid freon on the inlet side and as the heat from the piece of meat gets blown onto the coil the freon gets superheated and turns into a low pressure vapor. the superheated vapor then travels back to the compressor where it then becomes a high pressure vapor and the cycle starts allover.
So in the end we find that the system is not making things cold, rather it is removing heat from the space.