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How Automatic Defrost Saves Your Frozen Portable Air Conditioner Coils

frozen-air-conditoner--300Have you been thinking about the increasing weather these days?

It's so hot, even your portable air conditioner doesn't seem to be cooling your home.

If your answer to either or both of the aforementioned questions is yes, then there could be a major problem with your air conditioner.

Have you thought about checking to make sure there is no problem with the working mechanism of the cooler? If no, then read on and find out the best way to determine the problem.

Portable air conditioners provide convenience to their users, however, they are complex machines created for the purpose of providing you cool air during the warm months of the year. Often times you will face situations in which your air conditioner stops working properly.

One of the reasons for this could be that the evaporative coil present in the air conditioner is frozen. This serious issue must be handled immediately.

In this article, you will learn how to determine why your air conditioner's coil is freezing up, why it is so important, and what steps you should take to solve the problem.

What is an Evaporative Coil

In order to deduce how to deal effectively with your freezing evaporative coil problem, first it is important to understand what it actually is.

This coil, which is located deep inside the air conditioner, is considered the most important component. This component consists of a series of copper or steel coils that are covered by aluminum or steel fins.

  • The heat from the warm air that enters the air conditioner from your home and passes over the coil is removed, while supplying cool air to your home.
  • The evaporative coil is very important as it removes the humidity that is present in the air.
  • You must be wondering what this means. It means that the evaporative coil removes the moisture present in the air, thereby, providing you with cooler air. It is located alongside the condenser, which condenses and eliminates the humidity into the water.

Evaporative Coils - Reasons for Frost Built Up

It is very important to find out the various reasons which can lead to the freezing up of the evaporative coil. There can be different ways in which the evaporative coil can freeze.

Here are the reasons why evaporative coils can freeze, which can lead to low provision of cool air:

  • A frost line can appear on the evaporative coil. This can happen when the liquid refrigerant enters the evaporative coils and the temperature is as low as 10°F.
  • Usually, the warm air, which passes through your home and into the cooler, is enough to prevent the evaporative coils from freezing.
  • However, when the liquid refrigerant is released, which is present in the evaporative coil,without the presence of warm air, the liquid would immediately freeze over the coil's surface, forming a fine layer of frost.
  • The refrigerant is present within the evaporative coil, so that it could absorb the heat from warm air, whereby, the liquid refrigerant changes into gaseous state and provides cool air.
  • For efficient cooling, the gas is converted back into the refrigerant liquid, by placing the gas under high pressure.
  • This process creates extensive heat which is evacuated to the outdoors by the condenser coils, which is a second set of coils present within the air conditioner.
  • The refrigerant chills the air sent indoors by the air conditioner; however, without the presence of warm air the refrigerant overflows and leaks onto the surface of the coil, thereby freezing over it.

The building up of frost only stops when there is no more liquid refrigerant left. This occurs because the remaining refrigerant evaporated into warm air, and now without the cooler's coil, the temperature of the air will start rising.

The coil also regulates the pressure that builds up inside your portable air conditioner; however, with the frost formed over the coil, this ability becomes insignificant.

In order to ensure that the frost line ends at the coil, a proper refrigerant charge, which is the charge used to run the air conditioner smoothly, can be determined, or the correct adjustment of a metering device. This helps in ensuring that the frost stops at the coil.

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Most homeowners do not realize that there is a big problem on their hands, until they figure out that their portable air conditioner is running continuously without providing proper cooling.

Their air could be too warm or there could be a reduction in airflow. Assuming that the air conditioner is working just because you hear the hum of the machine, is an inaccurate deduction. If you start seeing that the exterior surface of the air conditioner is covered with ice, then it is high time for some prompt action.

The real cause for the reduction in air, or warm air being provided by the air conditioner is because of the frozen evaporative coil. The coil could be partially or entirely frozen, thereby, resulting in the decreased air flow.

In order to be certain that this is actually the case, you need to:

  • Remove the access panel of your disposable air conditioning unit
  • Inspect the coil present inside.
  • If you see that the area around the coil is sweating, then your coil is frozen. Sweating occurs because of the ice that had formed over the coil has come in contact with the metal casting of the air conditioner.
  • In some extreme cases, ice even starts forming on the exterior surface of the cooler.

single coilSteps to Take When dealing with Frozen Coils

  1. The moment you realize that the evaporative coil or the entire air conditioner is frozen, immediately turn it off.
  2. If your air conditioner system consists of heating mode, then switch it on and set it to heat up. Hot refrigerant will be pumped through the coils, which will defrost the frost on the coil's surface, while speeding up the entire process.
  3. However, it is very important to note the amount of frost that has accumulated over the coil. This is because defrosting it might result in the condensate drain overflowing with water, thereby, resulting in water damage.
  4. If you have a standard air conditioner, then turn the thermostat to the off option. Turn on the fan and allow the incoming warm air to help defrost the evaporative coil. You will find the selector switch at the bottom of the manual thermostats or along the side. Make sure to switch on the fan to help defrosting faster.
  5. There is one very important fact you should note; a heat pump can cause frost to appear on the outer surface of the condenser coil during the winter season. Because this occurrence is quite common, the heat pumps come equipped with the method to defrost the condenser coils.

While your frozen ac coil defrosts, you should check other things as well. Following are the various things that need to be checked to ensure that are no other pressing matters related to your air conditioner.


During the time when your coil starts defrosting, it is better to check the filters. If they are dirty, then they need to be changed. Dirty filters allow lesser air to flow through, which is the highest cause of frozen evaporator coils.

Throw away the dirty filters, and replace them with new ones. If you have washable filters, make sure to rinse it thoroughly to get rid of any kind of dirt.


  • Unless the manufacturer of your air conditioner recommends using soap to clean the washable filter, only use water to rinse it through.
  • Make sure to repeat this process after every 60 days during winter, so that your air conditioner remains in good working condition.
  • You can choose to check, wash, or replace them every 3 months during the rest of the seasons.


A dirty blower is another common cause of reduced airflow from the air conditioner. Blower is the term given to the fan that is located at the air handler. You will find it located close to or after the filters, and evaporative coils.

  • Sometimes even changing the filters on a regular basis is not helpful, because the blower cage can get dirt deposited and accumulated over its fins. This significantly affects the airflow and decreases it.
  • Check the foam gasket to ensure that it is in place, i.e. around the rim of the filter's frame.
  • Then check your operation manual and determine whether your filter is the correct size. Many of the evaporative coils are designed to allow airflow of 400 cubic feet per minute per ton of air conditioning.
  • With an air conditioning unit of 3 tons, you will require 1200 CFM of airflow across the evaporative coil; otherwise, it will become frozen.

Other than the aforementioned reasons, there can be a few other causes of frozen evaporative coils, which are mentioned below.

  • The fan belt is loose
  • The ductwork could have collapsed
  • The blower motor is not functioning properly
  • Return grilles might be obstructed, i.e. something could be blocking their way, for example, furniture.

Testing the Cooling Capacity of Your Air Conditioner

Before removing the panels and covers or checking the blower, make sure that the power is turned off.

  • Allow the coil to thaw, making sure not to rush the process.
  • Once you are entirely certain that all of the frost has defrosted, then replace the panels and the covers. Give the system a few minutes, before turning it on.
  • Turn the system to the cooling mode and then turn the fan back to AUTO. Make sure to check the system after every hour to check for proper airflow. This will also help ensure that the ice is not forming.

NOTE: It is very important that you do not use any sharp objects to try to hack at the ice that has formed over the coil. This action might result in the bending of aluminum fins, which will decrease the airflow. If you want to increase the process of defrosting then place a fan by the coil, it will help increase the flow of air.

In addition, if you take off the access panel, set it aside, and turn on the fan, then the blower will provide enough air to defrost quickly.

air-flow-symbol-85Automatic Defrost Air Conditioner

Automatic Defrost Air Conditioners come equipped with a built-in mechanism that allows them to defrost the frost on the surface of the evaporator coil, by proving required heat to it.

As the ice melts, the water is drained through a duct that is situated at the back end of the unit. This in-built defrosting can be controlled by an electronic timer that can be set for 6, 8, 10, 12 or 24 hours.

These hours are dependent upon the hours during which the compressor operates. After the set number of hours are over, the defrost heater automatically switches on and heats the coil for 15-60 minutes, depending on the extent of the frost.

Typically defrost heaters are equipped with power ratings that lie between 350W and 600W. In top and bottom models of freezers, this power rating is mounted below the evaporator, and in some side by side models, in the middle of the evaporator.

How well do units with automatic defrost perform compared to units without?

When compared with other types of units, automatic defrost air conditioning units perform optimally. The air conditioner's efficiency is either increased, or remains consistent with the automatic defrost. It also lasts longer than many other units last, and does not provide warm air.

In case where warm air is provided, it is better to contact your service provider and get the air conditioner checked by its manufacturer.

What other benefits are there to automatic defrost?

The option of automatic defrost in portable air conditioners offers many advantages, the biggest of which is optimal convenience.

  • Automatic defrost helps in saving a lot of energy and does not result in extra power consumption.
  • You no longer need to take care of the matter manually
  • The instances and chances of water damage are greatly reduced
  • The temperature is more effectively managed, particularly that of the hot air required to defrost the ice from the coil.
  • It automatically stops and switches to the cooling mode, once the process of defrosting is complete.

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