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Air Conditioner Troubleshooting Guide:
8 Most Common Problems and How to Fix Them

With hotter summers and colder winters, a properly functioning air conditioning system is essential for maintaining a comfortable indoor environment. However, even the most reliable units can experience occasional problems that require attention.

At Alliance Climate Control, we’ve put together a comprehensive guide to the most common air conditioner problems that we’ve encountered over the last two decades so you can diagnose and resolve the simple stuff on your own. From unpleasant smells to leaks, our guide explains why certain AC problems occur and simple video solutions you can follow to resolve them.

While our guide offers easy-to-follow solutions for simple problems, there are many other problems out there that are too complicated to self-diagnose or fix. In these cases, we strongly recommend consulting a qualified air conditioning repair technician like our local experts.

Air Conditioner Troubleshooting by Brand

Looking for a troubleshooting guide that covers a specific brand of Air Conditioner or Heater?

At Alliance Climate Control, we understand that different air conditioner brands may have unique features and requirements. 

That’s why we have developed comprehensive guides for our top 5 most popular AC brands:

These guides provide detailed information and step-by-step instructions on how to diagnose and resolve common issues that may arise with air conditioning systems from these brands. 

Whether it’s a problem with heating or cooling, unusual noises, water leaks, error codes, or connectivity, our brand-specific troubleshooting guides offer valuable insights and solutions. By utilizing these guides, our customers can effectively troubleshoot and address issues with their air conditioners, ensuring optimal performance and comfort in their indoor environments.

8 Most Common Air Conditioner Problems (with Video Solutions)

Below are some of the most common air conditioning problems that some of our customers have faced in the past with their AC unit or system. 

We’ve also tried to break down each solution into a simple to understand video to guide you through the troubleshooting process.

1. Why is My Air Conditioner Not Heating or Cooling?

Firstly, check the operation MODE on your controller. Regardless of the temperature you set it at, it needs to be set to HEAT mode to warm your home and COOL for it to cool down. Read your user manual or ask your technician to demonstrate the different modes and functions on the control panel as every mode button can look different.

2. Why is My Air Conditioning System Sometimes Louder than Normal?

If you have an inverter system, the volume of your outdoor unit will sometimes be louder than usual. This is normal. When the outside air temperature is very cold or very hot, the system needs to work harder to absorb or reject the heat from its surroundings. This means the compressor and the fan motor need to run faster, which increases the overall sound levels coming from the outdoor unit.

3. My AC System is Leaking Water/Steam from the Outdoor Unit. What should I do? Is this normal?

During normal operation in heating mode, the outdoor unit produces condensation. If you don’t have a drain installed on your outdoor unit, condensation may leak from the drain line or bottom of the unit, which is the water you may see the leaks are followed by blowing of warmer air than usual, it could also be a refrigerant leak. Refrigerant works to turn the warm air from your room into cool air. Either way, you should contact a technician to get your air conditioner looked at since extended exposure to refrigerant leaks can be extremely harmful to your body.

4. Why is My Air Conditioning System Not Heating or Cooling As Well As It Used To?

Throughout the working life of your system, it moves a lot of air around. This air carries dust and other airborne contaminants. Over time, these particles accumulate in your system, resulting in dirty filters that affect the efficiency of the system and its heating or cooling capabilities. Dirty air filters are usually the most common cause of drops in heating or cooling efficiency.

When was the last time you had your A/C system maintained? Your air conditioner’s filters are probably in need of cleaning or replacement.

5. Why Does My Air Conditioning System Stop Blowing Hot Air During Heating?

When your system is in heating mode, it needs to periodically defrost the outside unit, particularly when it is very cold. When this happens, the indoor unit stops blowing hot air or may blow slightly cold air. This usually only takes a few minutes before the system returns to normal operation.

6. My Air Conditioning Unit is Showing an ERROR Code on the Controller. What Should I Do?

If you see an error code, this indicates there is a problem. Some errors can be due to power fluctuation and can be cleared by resetting the A/C. You can reset it by turning OFF the power supply (isolator switch located next to the condenser fan) for five minutes. Then turn the switch back ON. If the fault reoccurs, make a note of the code, and call your Alliance Care team.

7. Why is My System Filter/Service Indicator Showing When I Only Recently Cleaned the Filter?

Contrary to popular belief, the filter indicator on most air conditioners is not a direct measure of how blocked the filter is. It is actually a built-in timer that is activated after a pre-set number of running hours. You can easily reset it, simply check in your user manual, or speak to your Alliance service technician.

8. I have Changed Internet Providers and Now I Can't Control My Air Conditioner From My Phone. How Do I Fix This?

If you have recently changed your Wi-Fi router or network provider, you may need to re-connect your system to your Wi-Fi network. Using the app on your phone, start the repairing procedure. The app will take you through the process step-by-step.

My Problem Isn't Listed Above, Does that Mean I Need Repair?

If you’re experiencing an issue with your air conditioning system that is not listed in our troubleshooting guide, it doesn’t necessarily mean that you need a repair. There are various other problems that can occur with AC units, and some may require professional assistance to diagnose and fix. Here are a few steps you can take before deciding on a repair:

  1. Check the power supply: Ensure that your AC unit is receiving power. Check the circuit breaker and reset it if necessary. Also, make sure the thermostat is set correctly.
  2. Inspect the air filters: Dirty or clogged filters can restrict airflow and affect the performance of your air conditioner. Remove the filters and clean or replace them if needed.
  3. Examine the vents and ducts: Ensure that the supply and return vents are not blocked or obstructed by furniture, curtains, or other objects. Additionally, inspect the ductwork for any visible damage or disconnected sections.
  4. Clean the outdoor unit: Remove any debris, leaves, or dirt that may have accumulated around the outdoor unit. Ensure that the unit is free from obstructions to maintain proper airflow.
  5. Check for unusual sounds or smells: If you notice strange noises or unpleasant odours coming from your AC system, it could indicate a more serious problem. In such cases, it is advisable to contact a professional technician for further evaluation.

If you’ve already tried all the above steps or are unsure about any of them, it may be best to reach out to an experienced and qualified air conditioning expert.

Alliance has been providing trusted local air conditioning services to NSW for over 15 years. Contact us today for an obligation-free quote on air conditioning repair today.

Schedule an appointment with
one of our specialists today.

Air Conditioner Repair vs Replacement

Deciding between repairing or replacing your air conditioning system can be a challenging task. Here are a few factors to consider when making this decision

If your AC unit is nearing the end of its expected lifespan (typically around 10-15 years), and the cost of repairs is significant, it may be more cost-effective to replace the system with a newer, more energy-efficient model.

Older air conditioners tend to be less efficient compared to newer models. If your current system is struggling to cool or heat your home effectively, a replacement unit could provide better performance and energy savings.
Evaluate the cost of repairs versus the potential benefits of a new system. If the repair costs are excessively high, or if you’re frequently encountering issues with your current unit, investing in a replacement might be a more sensible long-term solution.
Newer air conditioning systems are designed to meet higher energy efficiency standards. Upgrading to a more efficient model can result in lower energy bills and reduced environmental impact.
Consider the warranty coverage of your existing system. If the warranty has expired or is about to expire, repair costs may fall entirely on your shoulders. A new system often comes with a warranty that provides protection for several years.
It’s always recommended to consult with a qualified Alliance technician who can assess the condition of your system and provide expert advice on whether to repair or replace it.

Ultimately, the decision to repair or replace your air conditioner depends on the specific circumstances of your situation. Consulting with a professional can help you make an informed decision on air conditioner replacement, whilst ensuring that it suits your needs and budget.

Schedule an appointment with
one of our specialists today.

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