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DISCLAIMER: AS AN AMAZON ASSOCIATE I EARN FROM QUALIFYING PURCHASES. THIS POST CONTAINS AFFILIATE LINKS THAT WILL REWARD ME MONETARILY OR OTHERWISE WHEN YOU USE THEM TO MAKE QUALIFYING PURCHASES. FOR MORE INFORMATION, PLEASE READ MY EARNINGS DISCLAIMER.

If you think that air conditioners are designed to make cold air, that will not be true. An “air conditioner” is called that way for a reason, and that is because the air inside of this unit gets “conditioned” as a result of effective heat transfer.

A heat transfer is performed by evaporator and condenser coils. An evaporator coil has been designed to pick heat from the inside of your house and the condenser coil releases this heat outside.

Most residential AC units feature a split system configuration with a closed-loop refrigerant system:

Refrigerant inside coils

Refrigerant is a unique chemical that can continuously go through evaporation and condensation cycles. It circulates between the air conditioner’s evaporator coil and condenser coils while absorbing and releasing heat.

As the refrigerant moves through an evaporator coil (also called the “cooling coil”) it chills down a lot while maximizing its heat-absorbent properties. As it gets compressed and starts moving at the peak of its temperature through the condenser coil (also called “hot coils”), it releases loads of heat into the air.

This gets accomplished by the fan inside of the AC unit, which blows this heat energy through the condenser and outside. At the end of the condenser coil, it is back to its liquid state, and the cycle repeats all over again starting at the evaporator coil:

Before the refrigerant that comes from the condenser enters the evaporator, the high pressure is removed by the expansion valve. It is also responsible for turning liquid refrigerant back into vapor in order for it to be able to absorb more heat coming from your house.

Here is an interesting video on how the refrigeration cycle works:

Refrigerants How they work in HVAC systems

One of the biggest problems with AC units is a low refrigerant level. It impacts the performance and efficiency of your air conditioner and should be paid careful attention to.

The first signs that your refrigerant levels are low are:

  • Cooling problems
  • High energy bills

Low refrigerant levels may actually cool down your evaporator coil so much, that it will be covered with icing:

Frozen Air Conditioner

Brand new AC unit usually comes pre-charged with refrigerant and right before installation, your technician will check its levels. Refrigerant levels should also be checked by a professional after you test run your AC system for the very first time.

When maintenance is done by an HVAC professional, they will measure your refrigerant level and refill it if necessary. If leaks are detected, the evaporator coil, condenser coil, and all the connecting tubes in between will be checked for damage.

The Evaporator Coil

In the AC system, the heat extraction done by the evaporator coil:

As the warm air gets blown into the evaporator coil by the blower fan, the heat starts moving through the cool coils and gets absorbed by the refrigerant. The air cools down and gets blown back into your room.

This is how you get cold air on a hot summer day, but a lot of things have to take place before you get a constant cool airflow:

Upon absorbing all the hot air from the evaporator coil, the refrigerant is finished with the main part of its “work” inside your house. Now it will flow straight to the outside part of your air conditioning unit in order to start the cooling cycle.

This is where the condenser coil comes into play!

The Condenser Coil

An air conditioner system located outside your house is equipped with a compressor as well as a condenser coil.

As the refrigerant enters a compressor, it gets pressurized to the point where its temperature raises to more than 100 degrees. Heat energy molecules get concentrated and a superheated state is being created.

This process creates a significant difference in temperature between the refrigerant and the outside air. Since AC systems are primarily used in the hot summer season, the superheated refrigerant will still be hotter than the air outside, and heat will be released.

Now, I hope you can see that both condenser and evaporator play a very important part in the AC refrigeration system! If at some point you decide to upgrade a worn-down A/C unit, Goodman (paid link) is a good brand to consider. Sold on Amazon.

Evaporator vs Condenser

The design of the evaporator coil is similar to the condenser coil, only refrigerant in one of them heats up and in the second one, cools down. Maintenance for both coils is very similar and should be done with care according to the manufacturer’s specifications.

Another difference between evaporator and condenser coils are the type of individual maintenance they require:

Evaporator coil

This particular coil is prone to dirt and dust buildup because of the constant use of a fan blower. These particles can clog the coil and therefore making it work harder while producing less than perfect results.

Another problem specifically related to the evaporator coil is mold contamination. As the mold grows, it will have similar effects on a coil as dust and dirt (meaning less cooling and efficiency).

If any of the above problems are suspected, a certified HVAC specialist should be able to clean everything up.

Condenser coil

Due to its mainly outdoor location, the condenser coil is prone to many problems that come with it. First of all, all the cut grass, leaves, and just debris laying around on the ground could be easily a reason for the clogged condenser coil.

Hosing down the outdoor AC at least once a year should keep your coils in reasonably good condition. Don’t forget to SHUT DOWN the POWER before you do that!

There are three main “enemies” to the outside AC units:

  1. Trees. Things from the trees can fall and you should inspect the upper fan grille for damage as a regular maintenance procedure.
  2. Wind. Particles, like leaves, grass, and debris can fly right into the coil with a little assistance from the wind.
  3. Plants. We all like flowers and stuff, but not when they start growing around your AC unit! Nature doesn’t seem to care that you need an open space around your AC and could create a problem like that. This is something to watch for and cut vegetation down when needed (2-3 feet away).

So, the big difference between the condenser and the evaporator coil (in terms of conditions that they face) is that condenser coils usually do NOT grow mold, and lawn mover CANNOT clog your evaporator coils. Is it time to clean your coils? Well, without joking, they do have to be cleaned once in a while, so here is a nice, no-rinse, evaporator coil cleaner (paid link) for you from Amazon.


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