00
Thaw it fully
Gauges lie on a frozen system. If it's still iced when we arrive, we thaw it before testing, no shortcuts.
Switch it off, let it thaw, and read this before you run it again. Sydney wide, since 1991.
Ice on Your Air Conditioner?
Common AC Problems
What Causes an Air Conditioner
to Freeze Up?
Ice on your air con means one of two things, nine times out of ten. The system is low on gas from a leak, or the airflow is choked by dirty filters or a caked coil. Both make the coil run colder than it should, and it freezes the moisture straight out of the air.
First move: switch it to Fan mode and let the ice melt on its own. Never chip it off, the fins and pipes bend and puncture easier than you'd think, and a punctured coil turns a cheap fix into a dear one. Then get it looked at, because the ice always comes back until the cause is fixed.
On cost: a service call to find the fault is $250 plus GST. A gas top-up runs $200 to $350, a proper coil clean $200 to $300. We quote before we fix, every time. Full numbers on our pricing page. Since 1991, 4.8 stars from 280+ reviews.
0+
Years of Industry Experience
Licensed, Certified & Insured Technicians
Environmentally Responsible & ARCtick Certified
100% Service Satisfaction Guarantee
Flexible & Affordable Financing Options
Wide Range of Systems & Leading Brands
Quick Checks First
Before You Call a Technician
Turn the system off
Switch off Cool mode straight away. Every minute it runs frozen, the compressor is working against a wall of ice, and the compressor is the expensive bit of the whole machine.
Let it defrost completely
Run it on Fan only, or just leave it off. Depending on how thick the ice is, a full thaw can take a few hours. Put a towel down, melting ice means water, and a fair bit of it.
Check the filter
Once it's thawed, pull the filters and look. If they're packed with dust, wash them under the tap and let them dry. Choked airflow is one of the two big causes of icing.
Restart and observe
Clean filters, full thaw, then run it on Cool and watch the pipes for an hour. If frost starts creeping back, stop there and call us. That's low gas, and it needs gauges.
One Exception: Ice in Winter on Heating Mode
There's one situation where ice is part of the deal. In winter, on heating mode, the outdoor unit gets cold on purpose, and on a frosty Sydney morning it'll grow a light coat of frost. The unit knows. Every so often it pauses heating, runs a defrost cycle, steams like a kettle for a few minutes and gets back to work. Frost that comes and goes is normal. You don't need us for that.
What's not normal is a solid block of ice on the outdoor unit that never clears, in any season. That means the defrost system has failed, a sensor is lying to the board, or the gas is low. Same rule as summer ice: don't chip it, switch it off, give us a bell. If your heating is also struggling, the two usually go together, have a read of our not heating page.
And if the ice is on the indoor unit or the pipes in summer, that pairs with weak cooling almost every time. Our not cooling page covers that side of it.
Why It Happens
Why Air Conditioners Freeze Up
Here's what actually makes an air conditioner freeze up, in the order we find them across Sydney. The first two cover nearly every job.
Low Refrigerant (Most Common)
The big one. Less gas means lower pressure in the coil, and lower pressure means colder pipes. Cold enough and moisture in the air freezes onto them. The system is sealed, so low gas is a leak. We find it, fix it and regas. Top-ups run $200 to $350, leak repairs quoted before we start.
Restricted Airflow
Packed filters, a caked indoor coil or blocked return air. The coil needs warm room air moving across it to stay above freezing. Starve it of airflow and it ices over. Filters are a free fix. A chemical coil clean runs $200 to $300.
Faulty Expansion Valve
The expansion valve meters gas into the coil. When it sticks or blocks, the coil gets flooded or starved, and either way it can ice up. Less common, and we test for it properly before replacing anything. Quoted after diagnosis.
Low Outdoor Temperature
Running Cool mode on a cold night, under about 16 degrees, can ice some units even when nothing is broken. If you’re cooling a server room or a garage gym through winter, you need a unit rated for it, ask us before it becomes a habit.
Turn It Off Immediately
A frozen air conditioner that keeps running is paying for its own funeral. The compressor is built to pump gas, not fight a block of ice, and every frozen minute loads it up. Compressors are the one part where replacement often costs more than a new unit, so this is the fault you don't push your luck on. Switch off Cool mode the moment you spot ice. Fan mode is fine, it actually speeds the thaw. And keep a towel handy, because all that ice turns into water, and if the drain can't keep up it ends up on your floor. Already seeing drips? That's covered on our leaking water page.
Diagnosis Process
How We Diagnose a Freezing Unit
Ice hides the evidence, so a proper diagnosis starts with a thaw. Here's how a frozen-unit job runs.
00
Check filters, coil and airflow
We rule out the free stuff first. Packed filters and a caked coil cause a third of the icing jobs we see.
00
Gauges on
Refrigerant pressures tell us straight away if the system is low on gas, and how low.
00
Find the leak
Low gas means a leak, so we pressure test and trace it. Topping up without fixing the leak just books the ice a return visit.
00
Quote, then fix
You get the price before we start. Most icing jobs are sorted same visit, regas and clean included.
Real Jobs
Frozen Units We've Fixed
Daikin split frozen solid – Miranda
5kW Daikin iced from coil to outdoor valve, barely cooling for a week before the owner spotted it. Thawed it, pressure tested, found a slow leak at the outdoor flare. Re-flared, regassed with R32, frost gone for good. $350.
Ducted system icing the indoor coil – Glenfield
Panasonic ducted with ice on the coil and weak air at every vent. Return air filter was packed solid and the coil caked behind it. Chemical coil clean, new filter media, airflow back to spec. $290.
Mitsubishi split, pipes frosting over – Burwood
Indoor fan motor had slowed to half speed, so the coil sat too cold and the pipes froze. New fan motor fitted and tested, no ice since. $440.
Get Your Air Conditioner Running Again
Spotted ice on your unit? Switch it to Fan, let it thaw, and give us a bell on (02) 9820 4500. Family run since 1991, licensed (NSW 273312C), ARCtick certified (AU13058), 4.8 stars from 280+ reviews. Monday to Friday 7am-5pm, Saturdays by arrangement. We find the cause, quote it straight, and most frozen units are fixed the same visit.
FAQs
Frozen Air Con - Your Questions
Low gas from a leak or choked airflow, nine times out of ten. Both make the coil run below freezing, and moisture in the air turns to ice on it. The fix is a regas and leak repair, or a proper clean, and we tell you which before we start.
No. The coil fins bend and the pipes puncture easier than you think, and a punctured coil is a far dearer repair than whatever caused the ice. Switch it to Fan mode and let it melt on its own.
Frosted pipes usually mean low refrigerant. Less gas drops the pressure, the pipes run colder than designed, and they freeze the moisture out of the air. It’s a sealed system, so low gas means a leak that needs finding.
No. Running it frozen overworks the compressor, and the compressor is the most expensive part in the system. Switch off Cool mode as soon as you see ice. Fan mode is safe and helps it thaw faster.
A service call to find the cause is $250 plus GST. From there, a gas top-up runs $200 to $350, a chemical coil clean $200 to $300, and leak repairs are quoted before we touch anything. Most are done same visit.
Jay’s Air. Family run since 1991, our own blokes not subbies, fixed pricing and no surprises. Licensed (NSW 273312C), ARCtick certified (AU13058), 4.8 stars from 280+ reviews. Give us a bell on (02) 9820 4500.