Advice and News, Hints & Tips •
The days are getting hotter and you’re glad you invested in an air conditioner to offer some cooling relief. Until … it stops working properly (or not at all). Some issues can be resolved with regular maintenance and a little DIY knowledge. Others should be actioned by an experienced technician to ensure your safety and maintain the unit’s warranty. Here is our guide to common AC problems and how to deal with them.
The unit won’t turn on
There could be a few issues happening here, but the first thing to do is go to your electrical panel to see if the mains have blown. If so, turn them back on. This can often happen if the circuit is overloaded because the system is running too long. Then check that the shut-off switch on both the indoor and outdoor unit is disabled.
Reset your air conditioner to see if there is an alert. If there is, it’s probably the thermostat. Set the thermostat’s temperature at least five degrees below the inside temperature so you’re not overloading the circuit. If it still doesn’t work, it may need to be replaced. Or it could be due to another electrical issue such as loose electrical wiring or a faulty or clogged condenser fan. DO NOT attempt to fix electrical issues like these yourself – call in an air conditioning technician.
The unit’s not blowing cold air
This is another one of the common problems with AC. If your system is not blowing any air at all, or the air that is coming out isn’t cool, it could be due to a few issues, including:
- A tripped circuit breaker
- Wrong thermostat settings
- A blocked filter or drain
- Ice build-up on the coils
- Dirty coils
- Low refrigerant levels or leaks
First up, check your electrical panel for tripped fuses. Check your thermostat is set to ‘cool’ and at a temperature that’s at least five degrees below the inside temperature. Check the unit’s filter for dust and clean as required (see our guide here — this should be done at least twice a year before summer and winter). A blocked drain, dirty coils, ice build-up on the coils and low refrigerant levels or leaks should all be dealt with by an experienced technician.
The thermostat is out of place
Air conditioners have a thermostat sensor that’s located behind the control panel. This measures the temperature of the air the unit is blowing out. If it’s not blowing out any cold air, the sensor may have been knocked out of position. A technician will need to adjust it back into the right place. Also, get them to check the thermostat status on the remote. If it’s set to ‘on’, make sure it’s also set to ‘cool’ or lower the temperature to stop the unit being overworked.
It is leaking water or refrigerant
Condensation on your unit is normal, but excessive water could signal a leak somewhere or be due to a broken condensate pump or a condensate drain line that is clogged with dirt, dust or mould. If you see coolant lines along the unit and hear bubbling or hissing sounds, there could be damage to the coils and valves that circulate the refrigerant. This can be caused by regular wear and tear of components like rubber seals, copper pipes etc. Refrigerant is the chemical that cycles through your system to remove heat from inside your home and release it outdoors. With all of these issues, you should make an appointment with your technician, particularly if there is a refrigerant leak, as refrigerant is toxic and flammable.
Your air conditioner has a blown fuse
It is common for circuits to be overloaded in older homes if the unit shares a circuit with other appliances like irons, fridges and microwaves. This can be due to a tripped switch or blown fuse. The former we’ve discussed above, but if it’s not, it is probably a blown fuse. Again, never attempt any electrical work yourself, you’ll need to call a qualified electrician to fix it.
Unpleasant odours coming from your AC unit can make your living space uncomfortable. These odours are often caused by mould and mildew growth in the evaporator coil or ductwork. Regular cleaning and maintenance can help prevent microbial growth. Additionally, using high-quality air filters with antimicrobial properties can inhibit the growth of bacteria and fungi, which reduces the risk of unpleasant odours.
Sometimes, unpleasant smells may be a result of a malfunctioning condensate drain pan. You can mitigate this issue by ensuring that the drain pan is clean and free of debris. However, if the problem persists, it’s advisable to seek professional assistance to identify and eliminate the source of the odor.
Your system has ice build-up
Ice build-up is another one of AC common problems. If the fan blower is damaged, ice can form inside the unit and slow down its performance. To check, switch off the unit, lift the cover and look for any ice build-up. The only way to remove this is to turn the unit off and allow time for the ice to completely defrost. This can take anywhere from an hour to over 24 hours.
Your unit is on the wrong settings
Having the right temperatures set on your remote is crucial, but they can easily be changed. If your system is blowing air but still isn’t cold, make sure it is set to ‘cooling’ mode. This is typically indicated by a snowflake symbol or the words ‘cool’ or ‘cold’ on the remote. If it’s already in this mode, check the temperature is low enough for the unit to understand it needs to cool. You can test this by dropping the temperature to 16°C on a hot day to check if the air being emitted feels cool before you switch it to 24°C (the optimal level for power bill savings). The same goes for heating — if it’s blowing cold air, check the mode on your remote. A sun symbol typically denotes the heating setting.
During the heating cycle, if the unit’s blowing cold air, it might be because of the defrost cycle which switches to ‘cooling’ mode to allow the outdoor unit to heat and defrost. Some models also have the fan motor set on constant operation meaning the fan will operate regardless of settings, temperature and the defrost cycle. This can be switched off. If you’re not sure how to operate your model’s remote, search online, as most brands will have an instruction manual available that you can download.
It turns on and off continuously
This problem is called short cycling and is another one of the common AC unit problems. It occurs when your unit can’t complete a full cooling cycle and instead starts up in a continuous loop. This causes the compressor to turn on and off more often than usual, which can result in maintenance issues down the track. Short cycling can happen due to:
- The thermostat is not being calibrated properly
- Clogged filters that restrict airflow
- Low refrigerant levels
- A failing compressor
- An oversized unit
The first thing to do is check your thermostat is set on the right cycle and temperature. Place it centrally and not too close to the vents to ensure you get accurate readings. Next, check your filters aren’t clogged and give them a good clean. If none of these solves the problem, it could be due to low refrigerant levels or a failing compressor — both of these will need to be dealt with by a technician. If it’s due to an oversized unit, unfortunately, you will need to consider a smaller replacement.
Your AC’s compressor is worn out
Fan and compressor controls can wear out over time, particularly if they are constantly being switched on and off. A faulty or broken capacitor can also cause a compressor to stop working. An air conditioner can’t work without a functioning compressor, so it will probably need to be replaced. However, it is an expensive part to replace, so your technician may recommend you buy a completely new unit.
Your system’s ducts are damaged
If you have a ducted system installed, you’ll probably know that it transfers air through ducts in the ceiling. When this happens, air isn’t able to circulate through the system effectively. This will make the entire system work harder which will increase your electricity bills. One of the common AC problems with ducted systems are issues with damage by animals, including rats, mice and possums. Rats and mice in particular love ducting as it makes handy building material for their nests.
Rats and mice can also chew through electrical wires, refrigerant lines and other components of the system, causing all kinds of issues. If these types of animals (as well as geckos, snakes and cockroaches) start living in the system itself, your home can become contaminated with a toxic mixture of fur, urine and faeces. If you hear scuttling sounds coming from the ceiling, hire a professional to investigate. A technician will be able to identify and fix ducting tears.
If your system has been installed by a non-licensed technician, you are taking a gamble on the quality of the job. Problems like leaky ducts, incorrect refrigerant levels and out-of-place thermostats (and more) could occur, meaning you’ll need another licensed technician to resolve them. In Queensland, a refrigeration mechanic can only perform electrical work with an electrical worker licence or a restricted electrical work licence (refrigeration and air conditioning), so check their qualifications before booking them.
Like other complex machinery, air conditioning systems should be regularly serviced — at least once a year, although twice-a-year servicing (before the peak periods of winter and summer) is ideal. If problems are missed over time, the unit’s function and features will be compromised and may eventually fail.
- Kate King, 2023, 11 common air conditioner problems & how to fix them, Canstar Blue