What to do when your aircon isn’t blowing cold air?

When your aircon is running but not cooling, it can be incredibly frustrating – especially in the middle of a scorching Australian summer. If your aircon isn’t blowing cold air, there are several potential reasons why, ranging from simple fixes like dirty filters to more serious problems like refrigerant leaks or a broken compressor. Let’s look at some of the more common reasons your aircon isn’t cooling, what you can do to fix the problem and when it’s time to call in the pros.

In this article, we discuss: 

• Common reasons why your aircon is not blowing cold air

• How to fix an air conditioner that's not blowing cool air

• When to call a professional for your broken air conditioner

• Tips to prevent future air conditioner cooling issues

What are the common reasons why your aircon is not blowing cold air?

There can be a plethora of reasons why your air conditioning unit refuses to cool your room, but knowing some of the most common ones can help you pinpoint the exact issue: 

• Thermostat issues: It might sound very obvious, but one of the first things to check is the thermostat. Make sure it’s set to ‘cool’ and that the temperature is set lower than the current room temperature. If the display is blank or flickering, try replacing the batteries

• Dirty or clogged air filters: Over time, dust can accumulate in your system’s air filters. A clogged filter restricts airflow and makes it harder for cool air to circulate. In some cases, your aircon might keep running but fail to deliver that cold blast you’re expecting

• Ice build-up on evaporator coils: When airflow is obstructed or refrigerant levels are low, your unit’s evaporator coils can freeze. Ice that builds up will hamper the coil’s ability to absorb heat, which means your aircon air won’t feel cold

• Dirty outdoor condenser unit: The outdoor unit expels warm air from your home. If it’s clogged up with dirt and leaves, it won’t release heat properly – which in turn reduces the unit’s ability to cool air

• Low refrigerant levels or a leak: Your aircon uses refrigerant to absorb and remove heat from your indoor space. A refrigerant leak or low levels can make it impossible for your aircon to cool a room. This is not a DIY fix – you’ll need a licensed HVAC technician

• Compressor or fan problems: The compressor is the heart of your aircon, and if it malfunctions, the whole system can stop working. Faulty fans or worn-out parts will require servicing from a professional

• Electrical or circuit issues: If your aircon is on but not blowing cold air, check your power supply. Tripped breakers and blown fuses could be cutting power to main parts of the system

• Incorrectly sized aircon: If your aircon is too small for the room, it will struggle to cool it down. Likewise, if it’s too big, it might cycle on and off too quickly to properly dehumidify, making the room feel stuffy instead of cool

How to fix an air conditioner that’s not blowing cool air 

Now that you know what could be potentially causing your air conditioner to go on the fritz, there are a couple of things that you can do yourself to try and fix the issue before you reach for the phone to hire a pro.

• Clean or replace air filters: Filters should be cleaned or replaced every 1–3 months, especially during times of heavy use. This is one of the easiest ways to get good airflow

• Inspect the outdoor unit: Check your outdoor condenser unit for any visible junk. Gently clean the fins with a soft brush or hose, being careful not to bend or damage the coils

• Reset the thermostat: Try turning the system off, then resetting the thermostat to cooling mode. Set it to a reasonable temperature (around 22°C)

• Unblock vents and ducts: See that all vents and ducts are open and unobstructed by furniture or curtains. Good airflow is the foundation of proper cooling.

• Switch off the unit if coils are frozen: If you see ice on your indoor unit, turn off the system and switch to ‘fan only’ mode (or similar). This will help melt the ice. Don’t try and chip away at the ice yourself, as it can end up damaging the coils.

You might also like: Air conditioner maintenance checklist

When to call a professional for your broken air conditioner

If your DIY approaches haven’t resolved the issue, it’s time to call in a licensed professional. You should never attempt to:

• Refill refrigerant yourself (it’s regulated)

• Repair electrical faults

• Dismantle the compressor or fan motor

Tips to prevent future air conditioner cooling issues

• Book in annual servicing: Have your aircon professionally serviced once a year before summer starts.

• Clean filters regularly: Aim for monthly checks, especially if you use the system daily.

• Trim foliage around the condenser: Keep a clear space of at least one metre around the outdoor unit.

• Use a programmable thermostat: Reduce strain on the system by not overcooling your home.

The good news is it’s so easy to find a professional air conditioning technician near you.