What does it mean when your air conditioner freezes up?

Discussing the causes of a freezing air conditioner, how you can prevent an air conditioner from freezing, and how you can defrost the AC unit yourself.


As much as an air conditioner is meant to be a cooling system for your home, it should, under no circumstances, freeze up. This is not a good sign and is an indication that something is wrong with the unit.

In the case that you notice that your unit is developing a build-up of ice somewhere on it, it is important that you identify the problem in order for it to be fixed as soon as possible. An AC unit freezing can be caused by various functionality issues.

A freezing air conditioner

It is never a good sign when any part of an air conditioner seems to be freezing up, as it indicates that something more serious could be wrong with the unit. Air conditioner owners need to know what can cause their units to suddenly freeze up and what they can do to check and fix the issue.

There are a number of reasons why an air conditioner may be freezing up and some signs will not be as obvious as others, which could make it more difficult to pick up that your unit is malfunctioning.

What does it mean when your air conditioner freezes up?

An air conditioner is intended to cool a space by getting rid of the warmer air in a room. It is in no way supposed to start freezing up while doing so.

The biggest reason why the unit may be freezing is because there is little to no airflow. If there is not enough warm air blowing through the evaporator coil to transfer heat, the refrigerant will not turn to warm gas and will, instead, freeze.

Other possible reasons for your unit freezing up are clogged air filters that need to be cleaned or replaced; clogged condensate lines where water gets trapped near the evaporator coil and freezes; dirty evaporator coils restricting air flow that can freeze; and collapsed air ducts blocking air flow which can cause freezing and leakages, in turn causing low refrigerant levels.

Defrosting the AC unit yourself

One thing you can do to try to fix the issue is to attempt to defrost it yourself. You can do this by turning the system off using your thermostat. Switch the fan on to blow warm air onto the evaporator coils, and this can help speed up the defrosting process.

You need to give the evaporator coil or refrigerant line time to thaw and ensure that the frozen refrigerant does not end up in the compressor of the unit, as this can cause further damage to the unit.

How cooler summer nights can contribute to an AC freezing

At times, summer nights can be cooler than anticipated. Since air conditioners are built to operate at temperature thresholds, colder summer nights can sometimes be colder than the temperature thresholds that the air conditioner can withstand, and this will throw off the unit.

If you have a programmable thermostat, it could automatically attend to this issue by turning off the unit when the temperature suddenly drops to below 60 degrees Fahrenheit.

If you do not have a programmable thermostat, you will need to watch for temperature fluctuations yourself and adjust the settings accordingly.

How to prevent your AC unit from freezing

In order to prevent your air conditioner from freezing, you will need to be mindful of what causes it and keep certain components such as your air filters regularly changed. Make sure that you get an HVAC technician to service your air conditioner in the spring.

The technician will check for things such as dirty air filters, dirty or blocked evaporator coils, the level of refrigerant left, any blockages to your drain lines, and whether your fan blower is working at the proper rotation and speed it is required to.

Final thoughts

When an air conditioner is not functioning properly, there are times when you will be able to pick up on signs that tell you something is wrong. This is the case when a unit seems to be freezing, which it should not be.

There are a number of reasons that this will occur, and it is important that you identify the problem and figure out if you can fix it by yourself or require the services of an air conditioning technician. In some cases, you can defrost an air conditioner yourself safely.

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