Why does the air conditioner freeze up?

One of the most recurring problems is that the air conditioning freezes. This happens for various reasons and also manifests itself through different symptoms. In this tutorial, we’re going to start the other way around, with what we suggest to do (for those who are knowledgeable) and then with explanations of why) for those who want to dig deeper.
What to do when the air is not working properly?

1 – Clean the internal filters.

2 – Clean the interior and exterior exchanger.

3 – Clean the interior fan.

4 – If all this does not solve the problem of ice in the air conditioning, it is advisable to call the technical service.
How do I know that my problem is frostbite?

Good. Let’s then see the symptoms of why an air conditioner freezes.

Frozen air conditioning

Before we realize a fault in our air conditioning and depending on the type of this fault, our air conditioner usually gives us some symptoms that something is not working properly. These are the following:

1- The air conditioning does not draw enough air:

A drop in airflow is telling us something clear: not enough air passes through the indoor exchanger (indoor radiator).

The vast majority of air conditioners drive (pull) the same air that they suck or collect from the room where they are installed, so if the air conditioning freezes, this exchanger clogs as an ice layer forms on its entire surface, avoiding the entry of air into the machine and therefore its expulsion, resulting in a drastic decrease in the volume of air expelled by it.

2- The air conditioner throws ice or water:

Generally when the air conditioning freezes it tends to detach pieces of that ice and on many occasions, these pieces of ice end up entering the indoor fan (impeller – blades) which expels them to the outside while pushing the air into the room, sometimes the air conditioning throws ice and in others what is seen are drops of water when this ice thaws.

3- The air conditioner draws water inside:

As we mentioned in the previous point, if your air conditioner frosts or freezes, it is very possible that it will cause some of that ice to come off and blow it through the fan, but another possibility is that it will not throw ice and what it does throw be very cold water.

Another reason why an air conditioner spills water and this is the fault of freezing is because defrosting all the ice that forms in the indoor unit, causes the drain to overflow when too much water reaches the which cannot evacuate properly.

4- The air conditioning heats up little or heats up for a few minutes, others not and so on continuously:

Just as there is the possibility of a split indoor unit freezing, there is also the possibility that the outdoor unit of your air conditioner will freeze or frost when the heat option is being used.

This freezing will produce, as in the case of the indoor unit (cold mode), a plate of ice in all the external exchanger, preventing a good exchange of air in it and therefore lowering and decreasing the performance of our climate control.

This symptom is usually less noticeable since the vast majority of current air conditioners have a defrost or defrost function that largely prevents this from happening and its consequences, but also as this unit is outdoors, it is much more difficult to notice if the air conditioner freezes outside.

5- Noise in the indoor unit:

Sometimes “cracking” noises are heard in the indoor unit when the ice that accumulates in the machine thaws, this does not always happen, but it is a symptom that the machine can give us that something is wrong and will indicate that our machine may be freezing or thawing.

And why is this?

There are several causes that can produce this failure, some are not actually failures but lack of maintenance, others if are caused by more or less serious failures.

Dirty filters:

The most common cause and the easiest to fix is ​​having very dirty air conditioning filters.

This could have been avoided if we carried out correct maintenance of our equipment, basically, periodic filter cleaning and it is because not being able to pass enough air through the filters as they are so full of dirt causes the machine to freeze due to not being able to evacuate everything the cold it produces, the solution is easy, clean the filters.

Dirty indoor exchanger:

As in the case of filters, a dirty exchanger (indoor radiator) produces the same effect, there is not enough airflow through the indoor unit and it progressively freezes.

This problem is also usually due to poor maintenance since if we keep the filters of our air conditioner clean, they will prevent this dirt from passing to the exchanger and the problem of having to clean it.

The indoor fan is malfunctioning or extremely dirty:

If our indoor fan does not work properly due to a fault in it or because it is so dirty that it does not let air pass between its fins.


Lack of gas:

This is one of the most common causes. A partial lack of gas (if it lacks all the gas, the machine does not draw cold or freeze) will cause our air conditioning to freeze as if it were a freezer, since a drop in gas pressure directly affects a temperature evaporation rate (the temperature at which refrigerant reaches the indoor unit) lower, causing the indoor unit to freeze.

In heat function, the same situation will occur but this time the unit that would freeze would be the outdoor unit, the solution in both cases will be to look for the leak, repair it and finally recharge the gas.

Outdoor unit fan does not work or lacks ventilation:

In heat mode, if an outdoor fan does not work or has a lack of ventilation, it will cause the outdoor exchanger or outdoor machine to freeze.

This problem may be due to the fan itself being faulty or the electronic board not sending current, it will be solved by locating the source of the fault and repairing it, in this case it will be better to call a technician.

Very dirty external heat exchanger:

This fault affects when the unit is in heat pump mode, as we explained if the indoor exchanger gets very dirty.

A very dirty outdoor exchanger can cause the outdoor unit to freeze (in heat pump), the solution for both cases is to clean this exchanger.

Frozen condenser

The idea with these tutorials is that you can make a better diagnosis at home, and call the professional when it really is necessary.

Remember, the paces that must be recharged have a loss. Get that leak fixed first, then reload.

We hope we have helped you.

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