What Causes Air Conditioner to Freeze Up

Having an air conditioner can be a real lifesaver, especially during the hot summer months. It can provide a relief from the extreme heat, making sure that you stay comfortable. Nonetheless, there are also some instances wherein it can give you headaches, specifically when there are problems that can limit its functionality. Among others, one of the examples of the latter would be freezing.

This article will tackle what causes air conditioner to freeze up, and more importantly, the things that can be done to fix the problem. In most cases, the problem is simple enough to be handled on your own instead of having the need to pay a licensed technician. The key here is to properly identify the cause to determine the appropriate solution. When it is beyond your control and knowledge, do not hesitate to get in touch with experienced technicians to solve the problem.What Causes Air Conditioner to Freeze Up

Causes and Solutions to Air Conditioner Freezing

Below, we will list down some of the most common reasons why the AC sometimes end up being frozen, as well as the necessary solutions that should be undertaken to fix the problem as soon as possible.

Airflow is Restricted

One of the first things that can be blamed when the AC is freezing would be the air cooling coils. Over time, there could be dirt and debris that can block these coils, preventing the entry of air. If the air is not able to penetrate the coils in a proper manner, the cooling capacity will be minimized. There can also be a build-up of moisture, and it won’t take long before it ends up frozen.

There are many solutions that can be promising to solve the problem, but one of the simplest would be the replacement of the air filters. As it has been recommended by experts in AC repair, the filters should be replaced at least once in a month if you are using the unit regularly.

You might also want to inspect the blower or the fan that is located in the evaporator. It may not be turned on, which is why the airflow is limited.

Low Level of Refrigerant

If the problem is not with the airflow, the next possible reason why the AC freezes up is the refrigerant, which is most probably leaking. When there is a leak, the unit will immediately run out of Freon or refrigerant. The unit may still provide a cooling effect, but you will notice that it is no longer as effective as it used to be. Nonetheless, when the level is too low, the appliance will stop working.

To be able to properly determine if this is indeed the reason for the problem, a Freon gauge is necessary. If you are not a technician, you most probably do not have this tool. You can consider borrowing one instead of asking a technician to service the appliance.

Damaged Motor

If the motor of the AC has problems or damages, it can be the reason why it freezes up. To be specific, the blower motor can be the culprit. The main function of the latter is to blow the return air. If it is not able to blow return air to the coils, it will freeze.

In most cases, the problem with the motor can be a serious situation, and hence, we will not say that you have to deal with it on your own. This is one of those instances wherein it is better left to the pros.

Wrong Installation

If you have installed the unit on your own, chances are, there are problems with the installation which is why it ends up being frozen. For instance, if you have a window-type AC, keep in mind that it should be installed in such a way that it is slightly tilted, which will allow water to exit from the drain hole. If it is not able to exit, it might end up being frozen.

Another thing that deserves to be given emphasis in the installation would be the drainage. The drain pipe must be installed properly so that water will not be stuck inside.

Using the Unit in Low Fan

Especially for small window-type units, this is one thing that happens quite a lot of time. The coils may end up being frozen if you run the AC at a low fan mode. To avoid this problem, the most obvious solution is to always choose medium or high fan and not the low fan setting. This will push more air into the coils to prevent it from freezing.

Some of you might turn the unit to the coldest setting and when the room is already freezing cold, you will turn it to low fan mode. This is one thing you have to avoid as it does not only lessen the amount of air that is produced by the unit, but the coils can already be frozen.

Dirty Evaporator Coils

If the evaporator coils are dirty, it will be prone to freezing. It can accumulate gunk and debris through time, just like the air filters. If there is a lot of buildup in the coils, the tendency is that it will not be able to absorb heat and the cooling efficiency will be minimized. With this, evaporator coils should be cleaned regularly as part of the unit’s periodic maintenance.

Faulty Thermostat

The thermostat sends a signal to the AC to indicate that it should stop working when the right temperature has been reached, which means that the room has already been sufficiently cooled down. This is important for your comfort and to save energy. However, there are some cases wherein the thermostat may not work and hence, the cooling will continue.

If the unit runs continuously even when the peak room temperature has been reached, the coils will experience a cold temperature and this is the reason why it could end up being frozen. To solve this problem, the thermostat needs to be checked, calibrated, repaired, or replaced, depending on the extent of the problem that is apparent.

Low Outdoor Temperature

Do you live in a place where it gets extremely cold? The drop in temperature from outside of the house can also cause the AC to freeze up. If the outside temperature is lower than 62 degrees Fahrenheit, there will be a drop in the pressure in the AC. In turn, this is the one that will cause the freezing.


This article has tackled some of the causes of why an AC freezes up, such as having damaged motor, restricted airflow, leaking refrigerant, and wrong installation, among other things. Some of these problems can be fixed on your own. Others, however, are serious and would require expertise, which is why you are better off if you leave it in the hands of the pros.

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