Why Window Air Conditioner Compressor Not Turning On?

Compressors are responsible for regulating the temperature in a room by pumping the refrigerant around the air conditioning system to absorb the heat out of the room and deliver cool wind into it. The cooling process won’t start if the compressor does not turn on.

There are several reasons why a window air conditioner compressor isn’t turning on, including dirty coils and filters, or a lack of power due to insufficient power supply or damage to the air conditioner’s electrical wirings. Or the compressor may already be dead if the machine is old.

This article will help you find the reason why a compressor stopped working, which is the first step to repair your air conditioner. Then you can decide whether you can fix it yourself or if it’s time to hire a professional.

Reasons Why an Air Conditioner Compressor Doesn’t Turn On

Compressor problems can range from cheap to expensive, as you may only need to clean the air conditioner, or you may have to buy an entirely new air conditioning unit. As such, it’s crucial to first find out what keeps your compressor from turning on.

Coils and Filters Are Dirty

Over time, the evaporator coil and condenser coil become dirty and function less efficiently. 

The evaporator coil at the indoor part of a window-type air conditioning unit sits behind a filter that helps minimize dirt buildup on the coil. Too much dirt on the filter can also cause problems with the functions of the air conditioner.

On the other hand, the condenser coil at the outdoor part of the unit is exposed to seasonal changes and tends to accumulate dirt rather quickly. In addition to dirt, some leaves, branches, or bird droppings might get stuck into the machine.

If the coils and filters are dirty or clogged, this will cause more pressure on the compressor to work harder, overheat, and eventually stop working.

Lack of Power

The compressor is the starting point of the cooling process. If there’s no power supply, the compressor won’t turn on, and the process won’t start.

If the power supply is insufficient due to low voltage, the compressor will work harder and eventually overheat. This overheating can wear out the compressor causing it to fail.

Low voltage can be due to a mismatch between the voltage capacity of the power source and the requirement of the air conditioning unit. A 220V window air conditioner warrants a 220V power source.

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Another cause of low voltage is worn-out plugs or wires. An old machine usually has this problem, and it contributes to the decline in mechanical performance.

Multiple appliances plugged into the same power source can cause problems with each machine’s power supply. It’s bad for the devices and dangerous because it can cause fire to break out.

Compressor Is Dead

Individual parts of a machine tend to get worn out after years of use, and that’s pretty normal even if you perform proper maintenance checks.

Cleaning the coils and filter or ensuring that the wirings are in good condition can effectively extend the life span of the air conditioning unit. However, they won’t prevent a very old machine’s compressor from failing over time.

On the other hand, repetitive overheating can cause irreparable damage to the compressor more quickly, making it stop working altogether. When the compressor is completely dead, it’ll be impossible to make it run again.

What To Do When the Compressor Doesn’t Turn On

Instead of contacting an HVAC expert as soon as you notice a problem with your compressor, you may want to try some cheaper home remedies first.

Keep in mind, however, that some mechanical troubles require the help of an expert. Don’t attempt to repair the machine if the skills required are beyond you, as this may result in irreversible damage and bigger expenses.

Replace the Filter

Seasons change, and so does the amount of dust or pollen buildup on your air conditioner filter. Finding a good filter can help protect both your physical health and your machine’s health. 

A good rule of thumb is to replace the filter between 60 and 90 days. Inspect the filter every week and pat the dust out into the trash to slow down dirt buildup.

You can find a filter that fits the size of your air conditioning unit by checking your unit’s brand and model number or by measuring the actual size of your filter with a ruler. 

If you’re looking for a filter that can last an entire season, I recommend this AC Safe Filter (available on Amazon.com). It’s filtering power is superior to any after-market foam or even factory originals.

Clean the Coils

Cleaning the coils and replacing the filter regularly are two sure ways to prolong the life of your compressor and the whole air conditioning unit.

Remove any visible debris, such as fur, dust, leaves, and twigs that are stuck on your machine. 

If you want a handy fin comb to remove dust from the aluminum fins, check out this Supco Fin Comb Ring (available on Amazon.com). It works for various units and is easy to use.

If you don’t have the cleaning tools or are afraid that you might lose some screws while opening the unit and damage your unit in the process, schedule a complete unit cleaning with a professional HVAC cleaner once every two months.

Change the Power Source or Replace Faulty Fuse or Wires

Ensure that the air conditioner has its own outlet and circuit breaker and that the voltage of the power supply matches the voltage requirement. That is to say, if the air conditioner needs 120V, plug it into a 120V power outlet.

Unplug the air conditioner and check the fuse, wires, or plugs for visible signs of charring or burning. If they look fine, try to do a continuity test on the fuse using a multimeter to see if it’s in working condition.

Here’s a quick tutorial on how to do that:

Replacing these electric parts can be easy for handy people, but it can be dangerous and troublesome, especially if it’s your first time and you don’t have the tools. Therefore, it’s best to leave this task to experts to avoid further damage to the machine and harm to yourself.

However, if you want to do future continuity tests yourself, I recommend this AstroAI Digital Multimeter from Amazon.com. It’s features are good enough for professional and commercial use, thus guaranteed to handle any DIY task at home.

Replace the Compressor or Buy a New Air Conditioning Unit

You must contact an HVAC expert if you’re sure that the problem lies with the compressor itself. If the compressor is dead, only an expert can replace it.

After replacing the compressor, ensure that you perform a regular maintenance check on your machine, such as regular cleaning, to maximize the performance of your compressor and prevent it from malfunctioning again.

However, you must also assess the condition of the other parts of your air conditioning unit. If the unit is old and there are other problematic parts besides the compressor, it may be wiser to buy a new air conditioner.

Signs of Compressor Problems

To avoid irreparable damage to the compressor, pay attention to the warning signs. Noticing these signs early on can help prevent the necessity of buying new parts or a whole new air conditioning unit.

Compressor Doesn’t Start Immediately

If your air conditioning unit is fine, the compressor should start working immediately after you switch it on. However, if the compressor rumbles and takes time to start, it could be a warning that there’s a problem.

The problem could be with the power supply. If the compressor doesn’t receive enough power to start, it’ll cause some delays as it builds up the power to start running.

This can overwork and overheat the compressor, and it’ll eventually cause the circuit breaker to trip repetitively to avoid fire.

AC Unit Is Making Noise

The rumbling sound that you hear when you turn on your air conditioner is an indication that the compressor has mechanical or electrical problems. Watch out for other kinds of noise such as rattling, clanging, banging, or clicking.

Don’t ignore these sounds because a perfectly fine air conditioner wouldn’t make these noises. If you don’t have the technical skills to identify the root cause or address the problem, consult an HVAC expert immediately.

Air Coming Out Is Not Cool Enough

The compressor is called the heart of the air conditioning unit for many reasons, mainly because it compresses the refrigerant and pumps it around the system to effectively pull out heat from the room and deliver it out into the outdoor part of your window-type air conditioner.

If the air conditioner is not cooling the room as it’s supposed to, there are many possible reasons, including a broken thermostat, insufficient refrigerant due to leaks, dirty coils, or a faulty compressor.

Final Thoughts

An air conditioner is a machine, and it’s not meant to last forever. The compressor does much of the work in the entire unit, making it prone to all the problems mentioned above. All of these problems need immediate attention if you want to prolong and maximize the function of your air conditioner.