How Do Freezers Work? STEP By Step Overview

Freezers are one of those things we usually take for granted. Yet, we can’t imagine life without them, especially on those hot summer days.

However, knowing how freezers work is a great way to be more energy efficient. In fact, refrigerators and freezers make up nearly 6% of your average electric bill each month.


So, to help you cut back on this, read our how-to guide. After reading, you’ll know everything you need about your freezer, both inside and out.

How Do Freezers Work?

Freezers consist of a cooling system that works via a principle known as vapor compression. At the core of this system is a fast-moving vaporized refrigerant, such as hydrofluorocarbons (HFCs), that runs through two sets of coils. So, what does this refrigerant do exactly?

Step 1: Hot air enters the system

First, the refrigerant starts out as a hot gas. This vapor is put under low pressure until it enters the compressor, which is actually the heart of the unit’s cooling system.

Step 2: Compressor

The compressor squeezes out the vapor and sends it into multiple condenser coils. This is where the refrigerant loses heat and begins to cool down. As a result, the gas will condense and turn into a liquid.

Interestingly, though, this pressurization process generates heat. That’s the warmth you feel whenever you touch the outside of a freezer.

Fridges have this element as well but they don’t have to get as cold.

Step 3: Filtering the coolant

Next, the cool liquid is pumped into the capillary or metering tube. During this phase, any dirt particles and contaminants are removed from the liquid to get it ready for its next phase.

Step 4: Liquid to vapor

After that, the liquid refrigerant reaches the evaporator coils, where it converts the liquid back into a low-pressure vapor. The evaporator coils are also responsible for drawing heat away from the freezer system, thus effectively cooling all the items in your freezer.

This is a good time to mention that freezers don’t add coolness to the air; they consistently take away warmth, which forces temperatures within the freezer to drop.

Step 5: Closing the loop

Finally, the vapor returns to the compressor coils. As this entire process repeats itself, again and again, you get a consistently cold freezer system.

In fact, this thermal cycle can go indefinitely, given that none of the refrigerants escapes and that the unit has a functional power source.

Parts of a Freezer

Here’s a quick tour of the parts that make up your fridge/freezer unit.

Electric Motor

The motor drives the compressor and keeps the refrigerant pumping through the coils.


The compressor increases the pressure of the refrigerant gas and forces it to push through the cooling system. When the gas is compressed, energy is released in the form of heat, which you feel on the exterior walls of the freezer.

Condenser Coils

When the refrigerant gas leaves the compressor, it heads to the condenser coils. These are the small radiator-like loops on the back of the unit.

As the gas passes through them, it cools off and condenses. As a result, the vapor turns into a liquid where it’s then pushed into the dryer.

Capillary Tubes

Between the condenser and evaporator coils lie a set of narrow capillary tubes. This is a high-pressure area that helps remove dirt particles and remnants from the liquid before it’s passed on to the evaporator coils.

Evaporator Coils

In the evaporator coils, there’s a high-pressure expansion chamber. When the liquid passes through this chamber, it quickly reaches boiling point. As the liquid heats up, it expands and turns into a cold gas.

Ways to Keep Your Freezer Running Efficiently

Now that you know how freezers work, it’s time to learn a couple of things you can do to make sure yours is in optimal condition.

Take a look.

Regularly Clean Condenser Coils

Over time, dust, debris, and lint create a layer of grime on the fridge’s condenser coils. If it’s not cleaned and maintained on a regular basis, this can lead to poor performance and a deterioration of the system as a whole.

Also, while you’re at it, the inside of the freezer should also be emptied out and cleaned periodically. It’s not as difficult as you might think. Then, when you’re done, you can enjoy a gleaming, fully functional freezer.

Adjust the Thermostat

Experts recommend you set your fridge anywhere between 36℉ and 42℉. As for the freezer, it can be anywhere between 4℉ and 5℉, whereas chest, or deep, freezers can reach as low as 0℉ and lower.

These temperature ranges depend on two things: the weather and the amount of food within the unit. For example, during the summer, you should increase the temperature as much as possible to counterbalance the temperature outside the unit. Alternatively, you need to keep it at mid to low ranges.

Also, the more food you have stored in the freezer, the harder it’ll have to work to keep everything chilled. This would be a good time to raise the temperature slightly of your fridge/freezer unit.

The problem is that many of us don’t know what the appropriate temperature of our fridge/freezer unit should be. So, we turn it on way too high, which will overcool the items and cause freezer burn. Overcooling also forces the unit’s cooling system to work harder than it should and potentially damages the integrity of the unit.

The flip side is that we don’t turn it on high enough. Undercooling the items in your fridge/freezer means food will be susceptible to microbes. Thus, they’ll go bad and spoil at a faster rate than they normally should.

Maintain an Adequately Filled Freezer

As mentioned above, the more items you have in the freezer, the harder it’ll have to work to keep everything at a steady temperature. The best way to reduce the unit’s workload while boosting its efficiency is to keep it about two-thirds full.

This way, it’s not overflowing and wasting away too much energy. At the same, it’s not nearly empty, which can also add to the unit’s workload.

We have discussed how you can fix a frosting up freezer here. If your freezer is not freezing, we have listed some solutions here.

In Conclusion

Now that you know how freezers work, it’s time for a quick maintenance check. Use our tips to keep your freezer energy-efficient and sparkling clean.

You’ll thank yourself years from now when your unit is still in optimal condition. Plus, who can say no to lower electricity bills?