An air conditioner, like any other machinery, can suffer from neglect. If your air conditioner is not used for a long time, it can cause a number of problems.
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An air conditioner that is not used for months can become a breeding ground for mold and other bacteria. This can result in serious health problems for anyone who comes in contact with the air conditioner. Additionally, the neglected air conditioner can freeze up and damage the unit.
Let me share in detail why these happen to air conditioners and what you should do first if you plan to use them again. I’ll also give a few tips to maintain your air conditioner after letting it sit for a long time to prevent these problems from happening in the future.
What Will Happen to Your AC if It’s Unused for a Long Time?
If your air conditioner has been idle for quite some time, there are some things that you need to watch out for, from mold to damage in its electrical components. Let’s look at what may happen to an AC that hasn’t been used for a long time:
It Can Become a Place Where Mold, Mildew, and Other Harmful Bacteria Can Grow

One of the reasons a neglected air conditioner can become a breeding ground for mold, mildew, and other harmful bacteria is because it can become very dirty. If the air conditioner isn’t cleaned regularly, dust, dirt, and other debris can build up and make the perfect environment for these harmful organisms to grow.
Additionally, a neglected air conditioner can become a breeding ground for bacteria if you will not replace or clean the filters as much as you should. If the filters are clogged with dirt and other debris, they will not be able to function properly and will allow harmful bacteria to grow inside the unit.
Read: Can Black Mold Grow In Window Air Conditioners?
It Can Freeze Up, Which Can Damage the Unit
Another problem that can occur if an air conditioner is not used for a long time is that it can freeze up. This happens because the air conditioner’s coils are not able to circulate air properly when they are dirty. As a result, the coils will become very cold and can eventually freeze. If the coils of your air conditioner freeze, it will cause the air conditioner to malfunction and potentially damage the unit.
Also, when the air conditioner is turned on after an extended period, it can cause the coils to thaw too quickly, damaging the unit.

Read: Should You Give Your Air Conditioner A Break?
The Compressor Can Become Damaged
The air conditioner’s compressor is one of the most important parts of the unit, and it can become damaged if the air conditioner is not used for a long time. The compressor is responsible for circulating the refrigerant throughout the air conditioner, and if it is not used, the seals can become dry and cracked. This can cause the compressor to leak refrigerant, which will damage the air conditioner and make it less efficient.
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The Unit May Start To Rust
Rusting of air conditioners is one of the main problems for those air conditioners which are not used for a long time. This happens because the air conditioner’s coils are made of metal, and when they are not used, they start to corrode. Additionally, the air conditioner’s casing can start to rust if it is not properly protected from the elements.
Read: Is It Cheaper To Run A Portable Air Conditioner Or Central Air?
The Seals Could Begin To Leak
The seals are responsible for holding the refrigerant in, and if they are not used, they can become dry and cracked. This can cause the air conditioner to lose refrigerant, which will make it less efficient. And, if the air conditioner is turned on without the seals being properly lubricated, the compressor may fail.
The Freon Levels May Drop, Which Can Damage the Air Conditioner
Freon is the refrigerant that is used in air conditioners, and if the air conditioner is not used for a long time, the freon levels can drop. This can cause damage to the air conditioner because it will not be able to cool the air properly.
Its Electrical Components Can Become Damaged
Another problem that can occur if an air conditioner is not used for a long time is that the electrical components can become damaged. This happens because the air conditioner’s circuit breaker will trip. Additionally, the air conditioner’s electrical components can also become corroded.
The Air Conditioner May Stop Working Altogether
If an air conditioner is not used for a long time, it can eventually stop working altogether. This is because all the parts of the air conditioner can become damaged and corroded, and they will not be able to function properly. Also, the air conditioner’s filters will become clogged and will be incapable of circulating air properly.
Read: Why Window Air Conditioner All Lights Flashing And Beeping
How Do You Use an Air Conditioner After a Long Time?
If you want to use your air conditioner after it has been sitting for a long time, there are some things you need to do first.
- Clear any debris from around the air conditioner. Before starting up your air conditioner for the first time in a while, clear any stuff that may have accumulated around it. This includes leaves, dirt, and dust.
- Check the air conditioner’s filters. Once you have cleared away any debris, you should then check the air conditioner’s filters. Make sure that they are clean and free of any dirt or debris.
- Inspect the air conditioner for any damage. Search for any cracks or leaks in the air conditioner. If you find any damage, repair it before starting up the air conditioner.
- Lubricate the air conditioner’s seals. Doing so will help keep the air conditioner from breaking and also make it work better. If you need recommendations for lubricants, I suggest using B’laster Industrial Strength Silicone Lubricant (available on Amazon.com). This clear, non-evaporating formula eliminates wear from constant friction and is safe and non-staining.
- Check the air conditioner’s freon levels. Before running the air conditioner, you should also check the air conditioner’s freon levels. If the freon levels are low, be sure to recharge them before starting up the air conditioner.

Read: Why Air Conditioner Not Blowing Cold Air But Running?
How To Maintain an AC After Using It Again After a Long Time?
To avoid any problems with your air conditioner which has not been used for a long time, it is important to maintain it properly. Here are a few tips on how to do this:
- Check the air filter regularly and, if needed, clean or replace it. A dirty air filter will restrict airflow and make your air conditioner work harder than necessary. It will also make it more likely to break down.
- Inspect the unit for any signs of damage. If there are cracks or holes, contact a professional for repairs as soon as possible. It is better to be vigilant and catch any problems early rather than wait for them to cause more damage.
- Clean the air conditioner regularly. Just like the first time you cleaned it after many months of not using it, aim to clean the air conditioning unit at least once every few months. This will help prevent any dust or debris from building up and causing problems.
- Monitor the air conditioner closely. If the air conditioner starts making strange noises or sparks, turn it off right away and call a professional to fix it.
Conclusion
If you have not used your air conditioner for months, there are a few things you need to do before turning it on, such as cleaning any debris and checking the filters, etc. Also, it is crucial to regularly maintain your air conditioner to prevent any problems. Follow my tips above to ensure that your air conditioner is working properly and lasts a long time.