Last updated on August 25, 2023


It must seem a little strange to find a frozen evaporator coil in 40+ degrees out in Australia. A frozen coil may seem like a good thing – it means icy-cold air, right?

But unfortunately, ice on evaporator coils is an indication that something is wrong with the AC unit and neglecting the problem could burn out the compressor.

The good thing is that you can fix the problem all by yourself or you can hire for professional air conditioning and refrigeration repair.

Frozen Evaporator Coil Signs

If you suspect some problems with your AC unit, check for the following frozen evaporator coil signs

●     Open up your air handler and look for moisture and condensation.

Check for ice accumulation around the outdoor refrigerant line.

Is your condensate drain pan overflows? If the answer is yes, check for the clogged drainpipe.

If your AC unit shows any of the above-mentioned symptoms, it is notably important to resolve the issue as soon as possible or it may end up in some serious damage.

To understand the situation of frozen evaporator coils, let’s discuss the causes and their solutions.

Dirty Evaporator Coils

If debris, dirt or dust build-up around the evaporator coils and later transfer to the heat pump, it puts extra pressure on the AC unit for proper working, putting the coil at risk of freezing. A frozen coil can not efficiently absorb heat than needs periodically cleaning.

This is one of the prime reasons why it is essential to schedule yearly professional maintenance to avoid potential problems like this one. 


Hire professional air conditioning specialists once a year to avoid such problems. Make sure you use the proper equipment if you want to clean the evaporator coils yourself.

Refrigerant Issues

Since most of the refrigerants run in a closed system, you need not replace the refrigerant like Freon unless you notice some leakage in the system. Although leakage from regular wear & tear is very common. 

The leakage sometimes goes neglected for a long period of time and puts stress on the AC unit to work with low refrigerant levels, causing the accumulation of ice on evaporator coils.


There is no DIY solution of doing this. You must call in a professional to inspect your system for leaks and to restore the needed amount of refrigerant levels.

Airflow Problems

improper airflow from the blower can cause ice to build upon your evaporator coils. There are several possible reasons for insufficient airflow:

Undersized or damaged ductwork.

Blocked return grills and closed vents

Tight or improperly sized filter

Clogged air filter or duct coil

Dirty heat pump and air handler

Blower motor isn’t working properly


Most airflow issues can be solved with DIY cleaning. Replace the old air filters every month during peak use to avoid such a situation.

Inside & Outside Temperatures

When it’s cold outside, the heat pump and air handler will not function very well, causing the evaporator coil to freeze. A faulty thermostat is one of the possible reasons for inside and outside temperature variation.


Diagnose your thermostat regularly. Always put your thermostat to recommend setting while away from home. Avoid setting your thermostat too low as it can cause the Ac unit to freeze up, especially when it isn’t that hot out.

Drainage Problems

Various drain problems can make your evaporator coil to work hard to pass over the warm air. It could be due to 

Leakage & Flooding

Mould Growth

Clogged Drainpipe

These issues can cause the condensed water drops to head back and build up moisture which freezes on the evaporator coils, especially in humid climates. 


You will need to unclog your drain pipe to fix this problem. It involves a wet/dry vacuum. 


While you were inspecting and fixing the thermostat, refrigerant leak, airflow, dirty coils, and drainage problems, the frozen AC coils should have defrosted by now. 

Start planning preventative maintenance schedules, which include a professional inspection at least once a year.

It must seem a little strange to find a frozen evaporator coil in 40+ degrees out in Australia. A frozen coil may seem like a good thing – it means icy-cold air, right?

Posted onJanuary 22, 2020

Post Written by

Brendan Ward is a senior HVAC+R contractor, renowned in his industry as the go-to person for advice, design and planning of commercial air conditioning installations. Brendan has been a qualified professional in both the residential and industrial refrigeration and air conditioning sector for almost 25 years, and has owned Coalfield's Climate Control, a leading air conditioning company in the Hunter Valley for over a decade.

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