# Why is my air conditioner not cooling or heating properly? 1. [Home](https://arlite.co/) 2. [Support](https://arlite.co/support/) 3. [Air conditioning](https://arlite.co/support/air-conditioning/) 4. Why is my air conditioner not cooling or heating properly? **Browse support** [Support home](https://arlite.co/support/) [Solar](https://arlite.co/support/solar/)[View all](https://arlite.co/support/solar/) - [How does a solar power system work in a Brisbane home?](https://arlite.co/support/solar/how-does-a-solar-power-system-work-in-a-brisbane-home/) - [How do I turn off a solar inverter safely?](https://arlite.co/support/solar/turn-off-solar-inverter-safely/) - [Do solar panels work during a blackout?](https://arlite.co/support/solar/solar-during-power-outage/) - [Can I add a battery to my existing solar system?](https://arlite.co/support/solar/add-battery-to-existing-solar-system/) - [Hail or storm damage to solar panels: what to do](https://arlite.co/support/solar/hail-storm-damaged-solar-panels-what-to-do/) [Air conditioning](https://arlite.co/support/air-conditioning/)[View all](https://arlite.co/support/air-conditioning/) - [Why is my air conditioner not cooling or heating properly?](https://arlite.co/support/air-conditioning/air-conditioner-not-cooling-or-heating/) - [Why is my air conditioner leaking water inside?](https://arlite.co/support/air-conditioning/air-conditioner-leaking-water-inside/) - [Why does my air conditioner smell musty or like dirty socks?](https://arlite.co/support/air-conditioning/air-conditioner-smells-musty-dirty-socks/) - [Can solar panels run my air conditioner at night?](https://arlite.co/support/air-conditioning/can-solar-panels-run-my-air-conditioner/) - [What should I ask before getting an air conditioner installed?](https://arlite.co/support/air-conditioning/questions-to-ask-before-air-conditioner-installation/) [Electrical](https://arlite.co/support/electrical/)[View all](https://arlite.co/support/electrical/) - [Why does my circuit breaker keep tripping?](https://arlite.co/support/electrical/circuit-breaker-keeps-tripping/) - [Why does my safety switch keep tripping?](https://arlite.co/support/electrical/safety-switch-keeps-tripping/) - [Burning smell or hot power point: what to do right now](https://arlite.co/support/electrical/burning-smell-hot-power-point/) - [Why is there no hot water? 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By Amanda Cooper, Arlite Energy Last reviewed 30 October 2026 4 minute read **No DIY.** Electrical work must be done by a licensed electrician. Never open, repair, test or modify electrical equipment yourself, even if it looks simple. This guide explains what is happening; it is not a how-to. **On this page** 1. What makes an air conditioner stop cooling or heating well? 2. Why does it feel humid but not cold? 3. What should I do first? 4. Can I top up the gas myself? 5. Why might a newer unit still struggle? 6. What to note before you call 7. What does a technician do on a visit? 8. Frequently asked questions An air conditioner that is not cooling or heating properly usually has an airflow problem, a wrong setting, a unit that is too small for the room, or a refrigerant fault. Some causes are simple, but refrigerant and electrical faults need a licensed technician, so note the symptoms and call rather than investigating the unit yourself. ## What makes an air conditioner stop cooling or heating well? Most split systems, ducted systems and reverse-cycle units (one machine that both cools and heats) work by moving heat from one place to another. Anything that interrupts that process shows up as weak performance. The common causes are: - **Restricted airflow.** Dust build-up on filters or coils, or blocked vents, reduces how much air the system can move. - **A low refrigerant charge.** Refrigerant is the fluid that carries heat. It is sealed inside the system, so a shortage normally means there is a leak somewhere. - **The wrong mode or temperature.** A unit in fan or dry mode, or with a set temperature close to the room temperature, will not cool or heat much. - **A unit that is too small.** A system that is undersized for the room, or a room with a lot of sun or poor insulation, can run all day and never catch up. - **A fault in the outdoor unit or controls.** A failing fan, compressor or control board can reduce output or stop it altogether. ## Why does it feel humid but not cold? In Brisbane and across south-east Queensland, summer air carries a lot of moisture. An air conditioner has to remove that moisture as well as lower the temperature, so a room can feel clammy for some time after the unit starts. That can be normal on a very humid day, especially in a large or sunny room. If the room never reaches a comfortable level over a long period, the system may be undersized or have a fault. ## What should I do first? Using the remote or app as normal, check that the mode and temperature are suitable for what you want. Close doors and windows in the room while the unit runs. The owner’s manual explains the modes and the manufacturer’s maintenance guidance for your model, so it is worth reading. Do not open the unit, remove covers or try to adjust anything inside or outside. Stop using the unit and call if You notice a burning smell, smoke, sparks, a loud grinding or buzzing, or water around electrical parts. If there is fire, smoke or sparks, or anyone has had a shock, leave the building and call 000. For weak performance with no safety signs, contact an ARC-licensed refrigeration and air-conditioning technician or the manufacturer or retailer. ## Can I top up the gas myself? No. Refrigerant is sealed in, so it does not get used up like fuel. A low charge points to a leak, which needs to be found and repaired. In Australia, working with refrigerant requires a licence from the Australian Refrigeration Council (ARC), and DIY gas kits are not a safe or lawful option. You can find out more at [arctick.org](https://www.arctick.org/). ## Why might a newer unit still struggle? The size of the system matters as much as its age. A unit that is too small for the room, or one placed where the sun hits the room all afternoon, will struggle. A licensed professional can assess room size, ceiling height, sun exposure, insulation and layout to judge whether the system suits the space. ## What to note before you call 1. Describe the symptom — Write down whether the air is warm, cool or weak, and whether it affects one room or the whole house. 2. Record when it happens — Note the time of day, the weather, and whether the problem began suddenly or slowly. 3. Photograph the labels and display — Take a photo of the make and model label, and of any lights or codes on the display, without touching or opening anything. What you can safely check Look at the remote or app to confirm the mode and temperature, note whether doors and windows are closed, and read the owner’s manual. Do not touch, open or adjust anything on the unit itself. ## What does a technician do on a visit? A licensed technician will check how the system is performing, look at airflow and the condition of the indoor and outdoor units, and inspect for refrigerant leaks and electrical faults. They will explain what they find and what repair, if any, is needed. Keeping a note of your symptoms and photos of the model label makes the visit faster and more useful. ## Frequently asked questions - It could be the wrong mode, a defrost cycle, restricted airflow, a low refrigerant charge or a fault in the outdoor unit. If it continues, stop using it and ask a licensed technician to look at it. - Some delay is normal, particularly in humid weather or a large, sunny room. If it never reaches a comfortable level, the unit may be undersized or faulty. - It should not, because the refrigerant is sealed in. A low charge usually means a leak, which needs to be found and repaired by an ARC-licensed technician. - If there are no burning smells, noises, sparks or water leaks, normal use is fine. If anything looks or smells wrong, stop using it and keep clear. [Learn about Air Conditioning](https://arlite.co/services/air-conditioning/) Related services: [Ducted Air Conditioning](https://arlite.co/services/air-conditioning/ducted-air-conditioning/) ## Official guidance For the rules and safety information that apply to your home, go to the regulators and industry bodies directly. - [Australian Refrigeration Council](https://www.arctick.org/) - [Energy Rating (Australian Government)](https://www.energyrating.gov.au/) - [Electrical Safety Office Queensland](https://www.electricalsafety.qld.gov.au/) Was this helpful? Written by the team at Arlite Energy, a Brisbane business that designs and installs solar, air conditioning and electrical work for homes and businesses. We write these guides in plain English so you know what is happening in your home. ## Related articles - [Air conditioningWhy is there ice or frost on my air conditioner?Some frost on an outdoor unit in heating mode is normal, but ice on an indoor unit or on a unit in cooling mode points to a fault.](https://arlite.co/support/air-conditioning/ice-frost-on-air-conditioner/) - [Air conditioningWhy does my air conditioner keep turning on and off?An air conditioner that starts and stops repeatedly, called short cycling, often comes from sizing, airflow or a fault, and needs a technician.](https://arlite.co/support/air-conditioning/air-conditioner-turning-on-and-off/) - [Air conditioningWhat size air conditioner do I need for my room or home?The right kW size depends on room size, ceiling height, sun, insulation and layout, so a licensed professional should assess it.](https://arlite.co/support/air-conditioning/what-size-air-conditioner-do-i-need/) - [Air conditioningHow often does an air conditioner need servicing?Many manufacturers and installers advise servicing every one to two years, but follow your manual and warranty and use a licensed technician.](https://arlite.co/support/air-conditioning/how-often-air-conditioner-servicing/) ## Still stuck? Tell us what is going on and we can arrange a call-out. [Book a call-out](https://arlite.co/contact/) On this page 1. What makes an air conditioner stop cooling or heating well? 2. Why does it feel humid but not cold? 3. What should I do first? 4. Can I top up the gas myself? 5. Why might a newer unit still struggle? 6. What to note before you call 7. What does a technician do on a visit? 8. Frequently asked questions --- **Arlite Energy**, Unit 1, 1468 Anzac Avenue, Kallangur QLD 4503. Phone [(07) 3062 9299](tel:+61730629299), email [info@arlite.co](mailto:info@arlite.co). Monday to Friday, 7am to 5pm. Page: https://arlite.co/support/air-conditioning/air-conditioner-not-cooling-or-heating/ Site index for agents: [llms.txt](https://arlite.co/llms.txt), [sitemap](https://arlite.co/wp-sitemap.xml), [developer resources](https://arlite.co/developers/).