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What Is Compressor Lockout? (All You Need to Know)

Compressors are an essential part of various electrical appliances. All these appliances require a compressor to operate appropriately from refrigerators to heaters. But this essential component may face some issues while using.

You may hear about compressor lockout and may ask what this is. Let us help you understand what compressor lockout is and discuss some necessary facts and information related to it.

What is compressor lockout?

In appliances, a compressor may get overheated or jammed. This causes the compressor to malfunction and cause it to become unstable. A compressor has a safety mechanism that helps prevent danger by shutting it down. This is called compressor lockout.

Compressor lockout is an essential safety feature. Due to overheating and clogging, a compressor may become such unstable that it may cause it to become harmful to use. 

In this state, if the compressor runs any longer, it may cause the compressor to cause a lot of problems.

Overheating may cause the compressor to get seriously damaged or even create a life risk. Therefore, compressor lockout is a critical feature during these situations. It causes the compressor to shut down automatically. 

This prevents any damage to the compressor and prevents anything worse from happening.

Compressor lockout mainly happens when the appliance is working hard. While working hard to keep up with your requirement, it may stretch the compressor’s capability of operating. 

Thus, causing the compressor to overheat. Compressor overheating is not good and causes damage to the machine itself. Therefore, this safety feature helps to prevent that.

When the compressor gets clogged up or the air filters of the compressor get dirty, it causes the compressor to cause problems. To prevent any damage to the compressor, it enables its safety feature. As a result, it does a compressor lockout to prevent any major issues.

Lockout mode on a compressor means that it will not work until the user has manually reset it. Compressors have a reset button on them. When a compressor turns on lockout mode, you have to turn it on again by pressing the reset button manually. 

The compressor will not turn on until you do not press the reset button.

Can a dirty compressor cause high-pressure lockout?

A dirty compressor can cause a high-pressure lockout. High-pressure lockout happens mainly in the residential air conditioner systems. High-pressure lockout is caused due to the indoor unit or the compressor not getting sufficient air around it to operate properly. 

Therefore, due to this lack of air, the system ends up with a high-pressure lockout.

High-pressure lockout is mainly caused due to the lack of air around the indoor unit. Due to that, the compressor cannot get enough air to circulate. It can be caused by dirty condenser coils as well. 

Due to clogged dirt in the condensers, it blocks fresh air to get into the compressor. As a result, your compressor may get into high-pressure lockout.

Dirty compressors are the main reason behind compressor overheating. This causes the compressor not to get the necessary air required for cooling. As a result, the compressor tries to minimize or prevent any damage by turning off by high-pressure lockout.

What causes compressor lockout?

Compressor lockout is an essential safety feature for compressors. This helps prevent any damage to a compressor by automatically turning it off. There are particular reasons behind a compressor lockout.

You may ask what causes compressor lockout. Let us discuss the causes by discussing the reason behind why low-pressure lockout and high-pressure lockout occurs:

Low-pressure lockout

Leak in the system:

Refrigerant leak in the system causes the pressure inside the compressor to fall. When the pressure falls under a specific limit, the compressor starts overheating. Thus, the compressor’s low-pressure cutout trips and causes a low-pressure lockout.

Inadequate airflow in the indoor unit:

Sometimes, the indoor and evaporator coil gets clogged up with dirt. It may happen due to the dirty filters as well. As a result, the indoor unit will not get enough air in the system. 

This will cause the system to overheat its compressor which causes a low-pressure cutout.

Faulty low-pressure cutout:

If your electrician finds that your system is clean and there is no drop in pressure, then it is likely that the system has a faulty low-pressure cutout. It is rare to find that a system has a faulty low-pressure cutout. This may be due to the age of the system.

High-pressure lockout

Dirty condenser coils:

If the condenser coils inside the system get dirty due to the dust of the outside environment, then it may cause the system to overheat. This may cause a high-pressure cutout.

System having non-condensable:

If the electrician who was charging the system did not correctly dehydrate the system and keep any moisture in it, it is most probable that the system caused a malfunction. Due to the non-condensable in the system, it will cause a high-pressure lockout.

Overcharging the system with refrigerant:

If the electrician charges the system with more than 450 – 500 PSI of refrigerant, the high-pressure cutout may trip. As a result, the system will face a high-pressure lockout.

Condenser fan motor not running properly:

If the condenser fan in the outside unit does not run properly, the outdoor unit’s compressor will overheat. As a result, it will cause a high-pressure lockout.

What to do when compressor lockout? Can you unlock a compressor?

When a compressor lockout happens, you need to press the reset button on the compressor manually. The compressor lockout occurs when the compressor gets overheated. 

To prevent any damage, a cutout mechanism helps avoid any unwanted damage to the appliance’s compressor. Therefore, to start the appliance after a compressor lockout, you will have to press the compressor reset button manually.

Yes, you can unlock a compressor. A compressor lockout causes the compressor to lock itself for running until the owners do the necessary operations to unlock. 

To unlock a compressor, you will have to press the reset button or check the required checklist to identify the problem and resolve it to run again.

How to fix a compressor lockout? How to reset compressor lockout?

You may ask how you can fix a compressor lockout or reset compressor lockout. Here are the steps that you will have to do to fix this issue:

Check if your indoor unit has a clean filer and enough room for air circulation:

Dirty filters are one of the main reasons why a compressor lockout happens. Check if your indoor unit has a clean air filter or not. Also, check if there is enough room for the indoor unit to circulate air.

Check if the condenser fan motor is running:

The outdoor unit has a condenser fan to keep the compressor cool. If it is not running due to dust buildup or weak motor, it can cause this problem. Therefore, clean the fan and check if it is running or not.

Press the compressor reset button:

There is a compressor reset button in the outdoor unit of an air conditioner. It is necessary to press the button after a lockout occurs.

Check the pressure of the low and high end:

Even if the compressor does not run after pressing the reset button, you need to check if the pressure inside the low and high end are correct or not. Depending on that, you will have to charge or discharge.

Does this compressor lockout?

There are various brands and types of compressors available in the market. Some have this feature and some do not. You may ask which compressor has this feature. Let you investigate if some popular compressors have this feature or not:

York fs1:

Yes, York fs1 can compressor lockout. It provides multiple flashes on the control panel when get signal from a compressor lockout.


Yes, Nest can compressor lockout. When it hits the lockout temperature, it starts using the auxiliary heat on the system based on the lockout temperature is set on the system.


No, FSI cannot compressor lockout. Although FSI is a reputable brand for its product quality, it does not have a compressor lockout in its systems.


Yes, Carrier can compressor lockout. Carrier has a separate compressor lockout board on its system.


Yes, Trane can compressor lockout. It locks out the compressor when the temperature hits a lockdown temperature.

Coaxial freeze thermostat:

Yes, a coaxial freeze thermostat can compressor lockout. This is an old method of cooling systems.

White Rodgers thermostat:

Yes, the White Rodgers thermostat can compressor lockout. It is used in various air conditioners for its reliability.

Final Thoughts

Compressor lockout is a safety feature that prevents the compressor from overheating due to any problem and keeps it from danger. Although there are various lockouts, you have to enable the compressor by pressing the reset button in the compressor. Otherwise, the compressor will not run.