Why is my Air Conditioner Blowing Hot Air?

Tossing and turning through a night of restless sleep and waking up in a pool of sweat - while your air conditioning system is blasting - is a seriously frustrating experience. Matters are only made worse as you furiously poke at the turbo button in hope of drifting off into a chilly slumber. If you’ve found yourself in this situation and are wondering why your air conditioning system is blowing warm air, then you’ve come to the right place. There can be a number of factors affecting your air conditioning unit. While some solutions are quite simple, other matters can be more serious and may become expensive if the problem is left lingering. Here, we run through some troubleshooting steps that homeowners can undertake to ensure their air-conditioning unit is working to its fullest potential.

Ineffective Thermostat Settings

Having the wrong setting on a thermostat may seem obvious, however, it’s actually a common callout for customers whose air conditioning is blowing warm air. There are a number of settings that affect how cold your air conditioner is, but the most common is when a thermostat is set to heat, rather than cool. While the numerical temperature on the thermostat may be set low, if the setting is on heat you’ll be sending the cold air outside, and keeping the warm air inside.

Another lesser known trick for adjusting your thermostat to ensure cool air is being distributed is setting the air conditioning fan to ‘auto’ rather than ‘on’. If the ‘on’ option is engaged, then the unit will be running all the time - not just during the cooling cycle. This means that when the unit isn’t in the cooling cycle, it will be blowing out room temperature air and likely heating up a room.

The ‘auto’ setting means that the fan will only work with the room is being cooled. By ensuring your thermostat is set to ‘auto’ and not ‘cool’ you’ll keep both the temperature of a room - and your power bill - down.

Empty Refrigerant

If your air conditioner's blowing hot air because of a depletion of refrigerant, then this is likely a symptom of the problem, rather than the cause. Air conditioners operate on a closed loop system, so if your refrigerant is empty, there is a good chance there is a refrigerant leak somewhere in the system.

For this reason, it’s important to never trust a technician who simply tops up the refrigerant and assures the problem is fixed. A competent air conditioning technician should recognise that a lack of refrigerant is evidence that there is another problem with the air conditioner and undertake a full analysis to identify the issue.

Dirty Condenser Coils

Dirty air conditioner condenser coils can be a simple reason as to why your system is blowing hot air. Because the coils are located on the outdoor unit of your air conditioner, they are prone to getting dirty from dust, debris and other elements from the outdoor environment.

A coating of dirt on your air conditioner coils will insulate the coils from the surrounding air and reduce the efficiency of the heat transfer process.

Aside from not keeping your home as cool as you'd like, dirty air conditioner coils can create more negative problems. If dirty coils aren’t cleaned regularly, it can cause your air conditioners to work harder than normal and could result in your entire unit breaking down.

Air conditioner condenser coils should be cleaned at least once a year to ensure your unit works effectively. While this may sound simple, the condenser coils on an outdoor unit are extremely delicate and can easily be damaged if they’re not handled correctly. For a technician, this is a simple and straightforward job that can be carried out in a few hours.

Clogged Air Filter

A dirty air conditioner filter is another uncomplicated issue that may be causing air conditioners to blow warm air. Generally, filters should be changed approximately every 90 days.

Over time, an air filter will build up dirt that has been circulated through your system. This will cause a clog and, as a result, cold air will be trapped inside your air conditioner, causing ice to form on its coils. When this happens your air conditioner can freeze up and become inoperable.

An air filter will also catch allergens, like pollen, spores and dander, as well as bacteria. If the filter isn’t regularly cleaned out then, not long will it blow warm air, but these allergens will cause bad air quality and this can lead to physical symptoms, like sneezing, red eyes and congestion.

Changing a filter can be quite straightforward. However, many people don’t have the first idea of where to start when it comes to change a filter - or where to get the new filter from. A technician can quickly and easily change the filter for you.


Should I turn my AC off if it's blowing warm air?

The definitive answer to this question is a big yes. As discussed above, there is a myriad of reasons as to why your AC system may not be blowing hot air. Regardless of the specific problem, if your unit isn’t working effectively it’s likely to be working harder than normal in an attempt to cool down a room. The extra energy exerted from the unit won’t just cost you more in energy bills, it can put stress on the system which could cause a costly breakdown.

How do I reset my air conditioning unit?

A faulty air conditioning system can often be due to a tripped circuit breaker. If you’re lucky, a simple reset of your AC system may be all you need to do to get it functioning at full potential again. To reset your unit follow the following steps:

  1. Switch off your AC.
  2. Find your breaker box and look for the breaker that is connected to your air conditioner. Simply flip the switch off.
  3. Wait sixty seconds to ensure your unit fully powers down.
  4. After a minute switch the breaker back on and power up your air conditioner again.

Time to call the experts?

If you are still having issues with your air conditioner blowing warm air - it's time to call in the experts. Our Brisbane-based air conditioning repairs team are on hand to give you the assistance you need. Call us on 07 3283 5566 or fill out a quick quote to get your air con back up and running!

Experiencing other air conditioner issues?

Check out our other guides on common problems below:

My air conditioner heat mode is not working

My air conditioner will not turn off

My air conditioner is making a loud buzzing noise

My air conditioner is not turning on

My air conditioner is sweating inside

My air conditioner is icing up

My air conditioner is leaking water

My air conditioner smells bad

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