Home Improvement

Air Conditioner Troubleshooting: Problems and Solutions

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Hot summer days are a bliss in many parts of the world but in Australia, heatwaves can be harsh, sweaty and lasting for days. Folks, of course, can find refuge inside their homes in the hottest part of the day. But what happens if your air conditioning starts playing up? Simple. You’ll be heading for the nightmare of enduring sticky nights, tossing and turning in bed, unable to sleep. And in the day, you may be struggling to decide between jumping in a cool bathtub on your lunch break (if working from home) and sticking your head in the fridge to regain your mental clarity.

Joke aside, if this happens, it makes sense to have some idea about what the issue with your air-conditioning system might be while trying to cool down with a not-so-effective fan. You see, troubleshooting your ducted or split-system air conditioning may involve, just on the off chance, a straightforward problem and a simple solution.

This post will try to shed some light on what the issue might be if:

  • your air conditioning is not cooling your home the way it should;
  • it won’t work at all, as it doesn’t turn on;
  • you suspect a major fault with your central AC system and have trouble identifying it;
  • you can hear loud and strange noises coming from your air conditioning.

Most of the common air conditioning problems and solutions apply to any type of system, but some, of course, are specific to each, be it a window air conditioner, a ducted cooling-only conditioning or a split-system AC.

So, read on to see what might be the malfunctioning components with yours.

Table of Contents:

Common culprits behind failing AC systems & solutions to the problem

As you probably well know, ducted and split-system air conditioning systems consist of outdoor and indoor units, piping and lines, various connections, airflow outlets, controls and so on. And each of these components can break down or start underperforming. The result will be, your system begins to run inefficiently, your home is not warm enough in the colder months or, as we’re going to focus on here, your property is baking hot in the scorching Australian summer, instead of being nice and cool. Let’s dive in then and explore some AC problems and solutions in more detail.

AC is not cooling

Your central AC system may be running but it just won’t blow any cold air. Or worse, it can be actually letting warm air in the rooms – the last thing you’d want when it’s sweltering hot outside. Another grave issue you may have is an overheated air conditioner. A more palatable scenario is if your AC system is working but it’s not cooling sufficiently your home. Similar to a fridge that isn’t cooling, the reason behind these types of malfunctions could be more than one.

Possible causes

If the vents are not open (or only a few are open), or the thermostat/AC remote control is not set accordingly, this will lead to your AC not being able to let cold air in at all or enough to cool your home properly. Note that another reason for the system not cooling sufficiently your property, despite seemingly working fine, could be that it’s just too small for the size of your home. If none of the above is the case, then you most probably have more serious maintenance-related or technical problems on your hand.

Let’s list the most common of them:

  • dirty, clogged up filters
  • dirty condenser unit
  • frozen evaporator coils (due to blocked filters)
  • dirty (or frozen condenser coils)
  • electrical issues with the condenser fan (fan motor) and wiring
  • a broken thermostat (ducted system)
  • a leak in the refrigerant line
  • low refrigerant
  • insulation issues (ducted system)
  • damaged or clogged-up ducts
  • air loss, due to misaligned ductwork

The above-listed culprits behind your malfunctioning ducted AC or split-system air conditioning units can all result in your AC system not cooling sufficiently your property or at all. Most of them can also lead to overheated interior AC units.


You can, of course, remedy non-technical issues with your AC system yourself, be it setting the controls or thermostat accordingly (to Auto with the latter) and opening all the vents. You can also easily clean up the filters of your split-system AC units by removing them and washing with water and soap. This will prove harder with ducted-system filters, as they are not so easily accessible by a non-specialist. Last but not least, you can also give the condenser a good clean with a hose. Anything else that has caused your air conditioning to fail to blow cold air inside requires the expertise of a certified HVAC technician.

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AC is leaking water

Water dripping from your outdoor AC unit when in operation is expected, especially in hot, humid weather or if a small amount of frost build-up (in cold conditions when your system is in heating mode) eventually melts when temperatures rise. This applies to both split-system and ducted AC systems. If you have water leaking inside from your indoor AC unit, however, (or outside, when the system is turned off), then you’re looking at some sort of a problem with one or more components.

Possible causes

Below, you can check some of the reasons behind abnormal water leakage from your units inside or outside:

  • dirty filters
  • blocked drain pipes
  • a clogged condensate pan
  • a broken condensate pump
  • refrigerant gas issues (ex: leaks)


Again, with the above-listed scenarios, there’s very little you can do but call a qualified AC technician. This applies especially if you have a ducted AC system, as it’s not recommended to attempt troubleshooting or cleaning your interior or outdoor units (if leaking), as they and their components (filters, piping, etc.) can be awkward to reach and should be better inspected by an experienced professional. With small split-system AC units, you can try to remedy blockages yourself by cleaning the drain pipe or filters, but that’s about it. If unsure what you’re doing, we strongly advise you to leave the job to an expert.

AC won’t turn on

This situation can be frustrating if it happens unexpectedly, especially if it is scorching hot outside and say, you have some friends coming over any minute. Yep, you can change plans and move the dinner party outside by the pool, but still, you’ll need to eventually resolve your malfunctioning air conditioning.

Possible causes

Some of the causes behind your AC system not turning on can be simple and easy to fix yourself, whereas others will definitely require the expert skills of a certified HVAC technician.

  • flat batteries (AC remote control or thermostat)
  • wrong thermostat settings
  • tripped AC circuit breaker
  • a blown fuse


Naturally, your first course of action will be to check and replace if needed the batteries of your temperature control devices. If your ducted AC system fails to come on, investigate if the thermostat settings are as they should be (on cooling mode and at the desired temperature). It’s not a bad idea to also have a look if the outdoor condenser unit is running. Sometimes, lowering the temperature by about 10 degrees can resolve the issue. Note that you’ll need to study your thermostat manual, as it’s not that easy to program and calibrate the device if you’ve never done it before. The worst scenario could be a damaged motor or compressor, which unfortunately will have to prompt you to call in an accredited specialist.

AC won’t turn off

Although this problem is not affecting your comfort that much, meaning your home is nice and cool when needed in the summer or cosy and warm in the cool months of the year, your central AC system is designed to turn itself on and off via the thermostat. So, if it fails to do that, there is a problem.

Possible causes

Well, the reasons behind this can be in effect that you have an old and incorrectly-sized ducted AC system for your property that struggles to shut off as the temperature never reaches the desired level. Therefore, you may need to consider upgrading it. Other causes are often related to the actual thermostat. So, let’s check out what can be wrong with it and if there are any other possible culprits behind your continuously running AC system.

  • issues with the fan relay switches
  • a short in the thermostat wires
  • a broken thermostat
  • inappropriate refrigerant levels


Right then, there isn’t much that you can do to solve the problem, apart from switching off your AC system by turning the thermostat fan to the ‘off’ mode, which may help. Any other electrical or gas-related issues should be looked at by a professional HVAC expert. It’s just not worth it to mess about with AC components, as you can end up doing more damage than good.

AC makes noises

There could be various reasons for the noisy operation of your air conditioning. From rattling, screeching and banging sounds to clicking, smacking and thumping noises, they can be all generated, usually, due to a faulty or badly damaged mechanical part in your system.

Possible causes

As we said, in most cases, the cause behind any weird noises coming from your air conditioning system can be down to a malfunctioning component. But there could be, sometimes, gas-related reasons, as well. See below the list of common system faults that can make strange noises.

  • Dirty fan motor (screeching noise)
  • Deteriorating bearings (grinding/screeching noise)
  • Loose metal/flap in the ducts (popping noise)
  • Issues with the motor/blower (clanging noise)
  • Debris, stuck in the blower blades (smacking noise)
  • Worn out or misaligned belt (squealing noise)
  • Loose cover panels (rattling noise)
  • Relay problems (clicking noise)
  • Too much or too little refrigerant, due to a leak (high-pitched whistling noise)


As you can probably now guess, we would recommend, again, to call in a professional to inspect your AC system and investigate why it’s unusually noisy. You could check for debris stuck in the blower by yourself or add lubricant to the oil port to remedy fan motor and bearings issues, in order to eliminate certain strange sounds, but that’s.

AC fan is not working

When you have a malfunctioning outdoor or indoor fan, you’ll notice straight away, as your system will not cool your home as intended.

Possible causes

There could be a minor issue that you may be able to fix, in order to get the indoor fan or outdoor one going, but more often than not, this is rarely the case. Let’s see what you should be looking for:

  • Blocked filter (indoor fan not working)
  • Iced-up evaporator coil (indoor fan not working)
  • Faulty fan relay or fan belt (indoor fan not working)
  • Issues with the start capacitor (outdoor fan not working)
  • Damaged fan motor (indoor or outdoor fan not working)
  • Tripped breaker/ blown fuse (indoor or outdoor fan not working)
  • Dusty or rusty fan motor (outdoor fan not working)


If an easy-to-access filter is blocked, you can clean it and see if the indoor fan will get running. Also, you can try to reset the breaker/switch if it has tripped. Do not try to troubleshoot a non-turning fan for any other reasons by yourself, as you can get hurt or damage other important components. Just contact a specialist and patiently wait for their arrival.

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Why you shouldn’t attempt DIY troubleshooting your AC system

Central AC systems are complex to install, service and fix, and DIY troubleshooting carries more risks than benefits. Therefore, it is considered illegal for non-qualified people to do repairs on such complex systems. Any HVAC-related job requires qualifications, special equipment and skills. You may think that you’ll be saving a few dollars by getting your hands dirty trying to replace a faulty part. But the truth is that you will be faced with the following hazards:

  • Additional costly repairs – Do-it-yourself repair attempts of one part can lead to a serious breakage of another.
  • Jeopardised safety – Dealing with dangerous pressurised gases, toxic fumes and electricity can pose serious health risks.
  • Compromised efficiency – Substandard efficiency and higher monthly operational costs are often the results of unqualified AC repair work.
  • Invalid warranty – Manufacturers have put warranty conditions in place for a reason. Any unauthorised HVAC repairs will lead to your product’s warranty becoming void.

Convinced now not to tackle AC issues by yourself? Find a professional to take care of it.


  • An underperforming AC system is less efficient and has a shorter lifespan.
  • Regular servicing of your air conditioning can prevent future costly repairs.
  • Trying to resolve AC issues by yourself can be a risky business and it can adversely affect your system’s warranty.
  • HVAC repairs and AC maintenance are best left to the experts, who know what they are doing, and have the right tools and certifications.

Disclaimer: We are a commercial home maintenance service provider. Our purpose with this blog is to provide valuable and accurate content for solely informational purposes. We strongly advise our readers to consider all the risks and health concerns before taking a DIY project. We also highly recommend you get fully informed about the laws and regulations regarding electrical, plumbing and other work in the different states of Australia.

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