Troubleshoot Your Aircon: 8 Common Reasons Why Your AC Won’t Turn On

Tips / Troubleshooting

A working air conditioning unit has become an integral part of Australian living, as much as it has become an absolute necessity to the success of any business.

When your air conditioner stops working at the office or a large scale shopping centre such as Westfield Carousel, not only do staff members suffer so do your customers.

Unfortunately, in these circumstances, the issue is not so easy to diagnose and will generally require the help of a professional to repair and restore the system.

However, when your air conditioner breaks down at home, it might be a simple fix that you can do. But it can also be a major problem that will require a technician to come out and diagnose and repair.

Here are some common reasons why your air conditioner won’t turn on.

Potential Cause 1: Power Problems

Although this first one might sound self-explanatory, you sometimes forget to check the most common cause for your air conditioner not turning on – power issues!


Take a look to see if the power hasn’t tripped or if there is a blown fuse. This often happens in the sweltering summer when your air conditioner is working overtime to keep you cool, calm and collected.

To fix this, firstly check if your air conditioner is set to the “cool” setting. Change the temperature to 5 degrees colder than your current setting. If it is still not working, take a look to see if the circuit breaker is the culprit. You can do this at your electricity box to see if any of the switches have tripped. In true IT fashion, the question is always: “Have you tried turning it on and off again?”. If the issue is recurring, however, rather be safe and give the professionals a call.

Potential Cause 2: Faulty Control Board

Most air conditioners these days have something called a control board or PCB assembly. This effectively controls all the different small elements of your air conditioning unit. Because of this function, it can be extra tricky to figure out where the issue lies.


Don’t panic. If you can, check whether the compressor or fan circuits are not turning on. If not, the control board is more than likely the culprit for you having to sweat it out in the heat. Alternatively, a blown internal fuse could also be to blame, which you should be able to source and replace yourself.

Always check your user manual carefully before attempting to take on fixing the problem. And when in doubt, it’s always a good idea to rather call in the pros.

Potential Cause 3: Temperature Control Issues

If the temperature is not cooling in your home or office, then – you guessed it – the air conditioner’s temperature control unit might be the one to blame.

The temperature of your air conditioner is usually controlled by a sensor that scans the room to monitor the temperature. If this connection from the sensor to the electrical unit is faulty, the temperature will never cool down. Think of the sensor as your brain sending impulses to your body. In the same way, this connection is vital for your air conditioner to operate.


Check that your unit is getting power or that the fan is functioning by switching on the Fan Only option if your air conditioner has one. Listen carefully while you adjust the temperature to hear if the sensor and the electrical unit are connecting with a ‘click’.

Potential Cause 4: Thermostat is Defective

If your air conditioner is not turning on, the thermostat could be defective. Without a working thermostat, your air conditioner will be unable to know when it should turn on and when it should turn off, causing you to be uncomfortable in the sticky heat all day or night long.


Although it might seem obvious, did you check to see that the thermostat is switched on? If the screen is not on, it could’ve been turned off and is therefore easy to fix by simply switching it back on again.

If this is not the issue, try to replace the batteries to see if anything changes. If all else fails, it might be time to call in the professionals for their advice and/or to install a brand-new thermostat for you to cool things down.

Potential Cause 5: Clogged Drain Line

The condensate drain line could be clogged causing the issue. In order to operate, air conditioning units create condensation, which in turn goes through a drain line. Naturally, if this line is clogged, your air conditioner won’t turn on as a safety switch will trip to avoid serious damager or danger.


The simple answer to your problem here is to unclog the line. You could potentially use a shop vacuum or some sort of suction to open it back up again. Alternatively, if your air conditioning unit has a condensate drain pump to perform this function, it could be faulty and what is causing the safety switch to trip.

Potential Cause 6: Air Filter is Clogged

An old or clogged filter can cause your air conditioner to turn off or perhaps even freeze up.


Ensure that you are regularly (it is recommended that you do this about every three months) clean or replace the air filter in your air conditioning unit.

Potential Cause 7: Drainpipe is Flooded

If the pan under your indoor air conditioning unit is full of water, your air conditioner won’t turn on for safety reasons.


Clear it out and the issue should be resolved. If not, some other element could be causing the issue.

Potential Cause 8: Dirty Air Conditioner

If your air conditioner isn’t turning on, the cause could be as simple as: it’s dirty! If your evaporator coils or condenser lines are dirty, it can refuse to switch on.


Schedule a regular air conditioner service to ensure everything is and remains in tip-top shape.

Goya Keep your air conditioner running efficiently all year round

To ensure your AC system is running optimally all year round, it’s normal to have to have it regularly serviced and maintained for cleanliness, blockages and the odd repair by a licensed technician.

Regular Air conditioning maintenance and servicing of both residential and commercial AC systems not only increase its efficiency, it can also prolong the unit’s lifespan by up to 10 years.

If you detect any of these 5 Signs Your Air Conditioner Needs Servicing, it’s best to contact the professionals at All Air Services.

When your commercial air conditioner breaks down, not only does your business suffer, your customers do too. We understand the need for absolute comfort all-year-round, whether it be at home or at the office, and will work vigilantly to have your system up and running in no time at all.

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