Why AC can freeze up: Common reason and solutions

It's not an uncommon issue and it is often an easy fix

Written by Tomas Lyngen

Published: 08 Nov 2023

Why is my Aircon Freezing up?

Airflow is important for the aircon to work correctly and if air is not flowing, it's common the AC can freeze over and it can be multiple causes

Clogged air filter

If the inside air filter is completely clogged up, the AC is not going to be able to pull in air over the fins

Dirty coils

Over time, dirt will build on the fins and if they're not regularly cleaned. The airflow can be blocked and freezing can occur

Dirty or damaged fan

Inside the AC, there are fans that blow air over the coil. Inside these coils are cold gas and will blow hot air from the room over these coils to cool down the air. As the air keeps blowing over the coils, the gas inside heats up and are brought outside where outside air blown over the coils to cool them back down, before the gas is returned inside to repeat the processes

If these fans gets to dirty or damaged, this process will stop working and ice can start to build up

Here cleaning first needs to be done, then repair if anything is damaged

Refrigerant level is low

If there's a leak, the gas will be low in the system. The system will be less pressurized and your AC can start to freeze over

Possible solutions

Start here: Defrost system

A good place to start, is to defrost your system. This is something your AC normally handles itself, but if it's already frozen over. This is obviously not working and manual intervention is needed

1) Turn of your AC 2) Check your indoor filter and wipe off the worst of the dust 3) Check where the AC is freezing, inside, outside or both 4) Turn of AC and put it to fan. Do not use Auto, as this will automatically switch between cooling and fan 5) Let it run, so that the AC can defrost 6) This is a good opportunity to check if air is flowing inside and outside, which will tell you if fan is working or not. Please note that some AC will not run outside fan, while on fan mode and only as needed on cool mode

Clean AC

If it's been a while since the AC was last cleaned or that it's clearly dirty, it's time to clean the AC. The inside filter you should be able to clean yourself, but if you feel you're not able to clean the rest yourself. Getting help from professionals will be needed

Aircon cleaning (Window type): Regular maintenance