Portable Air Conditioner Compressor Keeps Shutting Off: Quick Fixes

Your air conditioner has a compressor that compresses the gaseous refrigerant into a liquid for cooling purposes. At times, this unit may keep shutting off making the air conditioner ineffective in cooling the house. There are many causes to this which you can fix yourself and some left for the experts. 

If the portable air conditioner compressor keeps shutting off, the causes include an overheating compressor, dirty condenser coils, insufficient refrigerant, and a faulty compressor or thermostat. To fix it, reduce the overheating, clean the dirty parts, and fix or replace the faulty parts.

If none of these solutions fix your AC compressor, it may be faulty and in need of a new one. If it’s a repeating problem, consider some of the best AC units you can buy as replacements.

Portable air conditioner compressor keeps shutting off

When the AC unit overheats, it triggers the overheat protection sensor which shuts it down. The overheating can occur in different parts with the compressor being one of them. Identifying the cause is the first step in fixing it. 

If the AC compressor shuts off after a few seconds or even after a long while, it could have the following issues:

The compressor is overheating

When an AC compressor is overheating, it’ll automatically shut down to protect itself and the air conditioner as a whole. You can test that by the time taken for the AC unit to start when it’s cold to when it shuts down by itself. The shorter the time, the higher the level of overheating. 

The overheating can occur due to a high compression ratio, old parts, clogs in the air compressor, or poor venting. 

• High compression ratio

A high compression ratio in the compressor means that the refrigerant is being squeezed into a smaller space than it should. This is mainly caused by low suction pressure which is in turn caused by improperly fitted parts, loss of refrigerant, and a drop in pressure.

• Old parts

Like all machines and moving parts, a compressor will struggle to be efficient when its parts wear out either due to old age or poor working conditions. When this occurs, the compressor will start overheating making it shut down after working for a while. 

• Clogs

Dirt in the compressor will clog up its tubes making it work harder to compress the refrigerant and push it to the other parts of the air conditioner. This produces heat which, if it reaches a certain unsafe level, will make the compressor shut down. 

• Poor venting 

The compressor can also overheat if its venting process isn’t working correctly. This allows heat to accumulate around it rather than being dissipated away. With time, the heat reaches unsafe levels which trigger the overheat sensor and shuts down the compressor. 

Dirty condenser coils

If dirt accumulates on the condenser coils, they’ll become ineffective at their role in the cooling process. Chemical reactions take place in these coils before the refrigerant is sent to the compressor and, if affected, will not take place. 

Eventually, the compressor doesn’t work as needed since it doesn’t receive enough refrigerant. It then shuts down. 

Insufficient refrigerant

The role of the air conditioner compressor is to compress the refrigerant into a liquid after it has cooled the house. If there’s too little refrigerant to cool, the compressor will shut down since its work and that of the air conditioner as a whole won’t be done effectively. 

An air conditioner can lose its refrigerate through leaks. As such, if your LG portable air conditioner compressor keeps shutting off, it could be due to a low amount of refrigerant. This also affects other brands of air conditioners. 

Faulty compressor

The compressor itself might be worn out or damaged to the extent that it can’t work as required. You can test your AC compressor as follows:

1. Unplug the air conditioner from the power for at least 30 seconds. 
2. Plug it back into the power supply. 
3. Turn the AC on. 
4. Adjust the settings as required. 
5. Wait for about 30 seconds then listen to check if it’s on or not. 

If it’s back on, the compressor is working right and it’s another issue altogether. 

Faulty thermostat

The thermostat controls when your compressor comes on or turns off in relation to the temperature of your house. If it’s obstructed or faulty, it might mistakenly read high or low temperatures in the house and turn off the compressor. 

Air conditioner compressor short cycling

Short cycling refers to a case where the air conditioner compressor turns on and off by itself. This is caused by having an HVAC unit that is too small for the room, icy coils, leaking refrigerant, or a faulty thermostat. 

Besides these issues, there may be a fault in the wiring, damaged or malfunctioning parts (condenser, compressor), and a defective AC unit. If you can’t identify any of the issues mentioned above, you may need to have an expert examine your AC before making a decision. 

How to fix an air conditioner compressor keeps shutting off

Whether the AC compressor that keeps shutting down is in a portable air conditioner or other type, the solutions to the causes of this issue are the same. 

Fix an AC compressor that keeps shutting down as follows:

Reduce overheating

Since overheating is one of the main reasons why the compressor shuts down, you should address it first. You can do so in the following ways:

• Reduce the compression ratio of the refrigerant

If there’s a loss of refrigerant due to leaks, fix the leaks or replace the damaged parts then top off the refrigerant. This should also do away with a pressure drop in the compressor. Lastly, fix any loose or improperly fitted parts on the AC unit as a whole. 

• Replace old parts

If you’re familiar with the workings of your AC unit, take it apart and replace any old parts you find. It may be as simple as a filter or pipes and ducts or a complex part like the condenser. If you’re not familiar with it, better call an expert on the issue. 

• Clear clogs in the compressor

Identify all the ducts and pipes in the compressor and those that lead to and from it then clean them out. You may need to take the pipes apart for proper cleaning. Before you refit them back to the compressor, make sure they’re properly dried up. 

• Provide proper venting

You can properly vent the air conditioner by straightening the pipe from it to the outdoor parts to avoid any kinks and sagging. You can also place the AC unit further from the window to remove any sagging on the pipes. Finally, you should clear any clogs in the pipes which may be accumulating excessive heat. 

Clean the condenser coils

Condenser coils tend to accumulate grime and other types of dirt which reduces their effectiveness. Always check and clean them with a coil cleaning solution such as Nu Calgon. This can be done at least once a month to keep the coils clean. 

Recharge the AC (refill the refrigerant)

You should first identify the reasons why there’s insufficient refrigerant in your AC unit. If it’s a leak, fix the leak first then add more refrigerant to the unit. This task might be too complex for some people hence the need to enlist a technician. 

Replace the compressor

A faulty compressor needs to be replaced as soon as possible to restore the working of your AC unit. Replace the compressor in your air conditioner then test it out as detailed above.

Fix or replace the thermostat

If the thermostat is simply obstructed or wrongly set, you can fix it to its normal working state. Otherwise, you’ll need to replace it with a new one for the air conditioner to work properly.

At times, the main issue isn’t one of the problems mentioned above and is on another part of the AC unit. You may experience other problems as well such as an AC that sounds like a jet. As such, make sure the AC is on the right working settings, the filters are clean, and the wiring is done correctly. If none of these fixes solve your problem, it might be time to go for a new AC unit.

Tim David

HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.