LG Air Conditioner Compressor [Problems & Proven Solutions]

An LG air conditioner compressor is the heart of the system. Without it, the unit cannot function. So, it is crucial to find permanent solutions if the compressor becomes faulty.

LG Air Conditioner Compressor Keeps Shutting Off – What to Do

The following are things to do if your LG air conditioner compressor keeps shutting off:

1. Check for Overheating

The compressor may automatically shut down due to overheating. To test this, allow the air conditioner to be off for an hour so that the compressor is not hot. Next, turn it on to see if the compressor runs for a long period without shutting off again.

If the compressor runs without a hitch, you know it is an overheating problem. Ensure the condenser fan is working and the refrigerant level is not low. Low refrigerant can cause the compressor to work harder to compensate for the loss, leading to overheating. And the fan, which should cool the condenser and compressor, can biome faulty and leave the compressor to overheat.

If the refrigerant is the problem, only a certified HVAC technician should inspect the system. That way, they can find leaks and seal them before recharging the system with refrigerant. Adding refrigerant without fixing leaks will only lead to the refrigerant leaking again. Besides, it is unsafe to inhale large amounts of refrigerant.

Power fluctuations can also cause the compressor to overheat. So, check the electrical wiring and systems in your house. You will need the services of an electrician to check the wiring and grid to ensure everything is in order.

2. Check the Condenser

Open the outside unit and check the condenser. If you have never cleaned it and the air conditioner has been in use for a while, the condenser must be dirty. So, use a small and soft brush to clean the fins of the condenser to remove debris. Do it gently because the fins are pretty fragile and damaging them destroys the condenser.

Dirt on the condenser contributes to overheating. One of the condenser’s jobs is to transfer heat out of the system to enable efficient cooling. But when it is considerably dirty, the dirt insulates it and prevents the heat from leaving the system. As a result, the compressor overheats even with the fan running and with time, the air conditioner stops cooling.

3. Check for a Short

There may be a wiring short inside the compressor. If that is the case, the compressor is compelled to draw more voltage than usual to make up for the loss. Consequently, the voltage causes it to overheat. 

Typically, the overload protector should prevent this from happening but if the compressor draws voltage constantly, the device will burn out. Only a technician can check the compressor and determine whether or not there is a short. A multimeter test can also tell you if the compressor has continuity. If there is no continuity, it may indicate a short. The technician will let you know if it can be fixed or you need a new compressor.

4. Check the Temperature and Mode Settings

Setting the air conditioner temperature to the same point as the room temperature shuts the compressor off frequently. If the room and air conditioner temperatures are the same, the compressor will turn off until the room temperature rises above the unit’s set temperature. Then, it turns on again to lower it.

While adjusting the temperature to a lower point, and ensuring it is a few degrees lower than the room temperature, check the mode. You need to use the Cool mode if you want cool air. You can also set it to Auto for the compressor to run efficiently.

5. Check the Drain Line

A clogged drain line will cause water to store in the drain pan. When the drain pan becomes full, it triggers a switch that shuts the air conditioner down. Use a wet/dry vacuum to clean out the drain line. A mixture of vinegar and water poured down the drain line will also clear it. That way, the pan does not fill to overflowing.

6. Check the Air Conditioner Size

When an air conditioner is bigger than the size of the room it cools, the compressor tends to shut down too frequently. It is crucial to purchase an air conditioner with the size of your house in mind. Compare the square feet of the house with the corresponding British Thermal Units (BTUs). That way, the compressor will not keep shutting off.

7. Check the Circuit Breaker

An insufficient supply of power from the breaker can turn the compressor off too often. Check the breaker for the air conditioner; turn it off and on within thirty seconds and wait for the compressor to run.

If the compressor runs and shuts off again, it may be a problem with the breaker. Turn off other electrical appliances in your home and try running the compressor again. If the compressor goes off, the breaker is not the problem. But if it does not, it means other devices are connected to the same breaker as the air conditioner, reducing the voltage. Have an electrician reroute the appliances to another breaker and leave one dedicated to the air conditioner.

LG Air Conditioner Compressor Won’t Shut Off – How to Fix

The following are components to check and how to fix them if an LG air conditioner compressor keeps running:

1. Temperature Control Thermostat

Using a multimeter, run a continuity test on the thermostat to determine whether or not it has continuity. If the thermostat registers continuous continuity, it means the component has a short and needs a replacement. If the air conditioner has a heating element, the thermostat may also control it. So, it may have more than two terminals. The unit’s wiring diagram will help you run the test and other diagnostics.

It is the job of the temperature control thermostat to send voltage to the fan and compressor when necessary. A shorted thermostat may continuously send voltage to the compressor, causing it to run without shutting off.

2. Condenser

Open the outdoor unit and check the condenser coil. If it is dirty, which it likely is because of its location, clean it with a soft brush. Make it a duty to clean the condenser once a month to keep it in optimum shape. Be careful with the fins so you do not damage them due to their fragility. Also, clean the area around it, at least up to two feet.

Dirt forms insulation around the condenser, restricting it from dissipating heat from the air conditioner. If the heat remains trapped within the system, the compressor will put in extra work to help the unit perform efficiently. The extra work keeps the compressor running around the clock.

3. Air Filter

When the air filter is dirty, it restricts airflow and causes the compressor to run continuously as it tries to make up for the air restriction. You will notice a reduction in the production of cool air. Remove the air filter from the air conditioner and clean it with a vacuum. Wash it in soapy water if necessary, but allow it to dry completely before putting it back in place.

4. Refrigerant

If the amount of refrigerant in the closed system is lower than the air conditioner needs to run, the compressor will run all the time to cover for the loss of cooling. The system can lose refrigerant from leaks in the line or damaged coils. If you suspect a loss of refrigerant, it is best to contact LG to report the issue and request service or hire a qualified HVAC technician.

5. Evaporator

The evaporator coil is where the refrigerant absorbs heat and produces cold air. The blower circulates the cooled air in the room. But if the coil becomes frozen, which happens when the filter is dirty, it cannot work as it should; the ice insulates it. As a result, the compressor runs more than it should in order to provide cool air. Turn off the air conditioner and leave it without power until the ice on the coil melts. You can also use a hairdryer for the same purpose.

6. Thermistor

The thermistor is a sensor fixed to the control board. Its job is to sense the air temperature and signal the board to turn on the cooling system. If no other part seems to be the source of the problem, test the thermistor using a multimeter. Replace the component if it shows no continuity when it should. Otherwise, it may wrongly signal the board to power the compressor, causing it to run non-stop.

7. Relay Board

Much like the temperature control thermostat, the relay board supplies voltage to the compressor. If there is a fault with the board, one of the ways it manifests is the constant supply of voltage to the compressor, keeping it running all the time. However, it is crucial to diagnose the board correctly because boards are often misdiagnosed and they are hardly ever the cause of the problem. Check other parts before checking the relay board.

8. Thermostat

Check the internal thermostat of the unit. First, set the air conditioner to cooling mode. Then, run the continuity test on the thermostat to check for continuity. While in the cooling mode, the thermostat should show continuity but if it does not, replace it. Consult the unit’s wiring diagram for how to check the thermostat if it has more than two terminals.

The thermostat keeps an eye on the temperature of the air to activate a switch when it rises. When it powers the switch, the compressor and fan run. But if the thermostat fails, the compressor may run without stopping.

9. Air Conditioner Size

An air conditioner that is smaller than the room size will run too frequently as it tries to cool the space. You may have to exchange the unit for one with a more adequate cooling capacity if you want to solve the problem. Not only does it wear the compressor out but it also consumes too much energy. Always purchase air conditioners using its British Thermal Units compared to the square foot of the space where you want it.

The main and temperature control boards may also contribute to how often the compressor runs. Since they control most of the activities of the unit, faulty boards affect different components. But like the relay board, do not replace the boards before checking other components. If nothing else works, check and replace the boards.

Check out these other articles…

How to Reset an LG Air Conditioner [Quick Guide]

LG Air Conditioner Not Turning On/Not Turning Off [How to Fix]

LG Air Conditioner Turns On and Off By Itself [Problems Solved]

LG Air Conditioner Blinking/Flashing [Quick Fix]

LG Air Conditioner Not Blowing [How to Fix]

LG Air Conditioner Blowing [Issues & Solutions]

LG Air Conditioner Not Working [Problems Solved]

LG Air Conditioner Compressor Not Working – Solved

The following components are the most like to cause the air conditioner compressor to stop working:

1. Temperature Control Thermostat

Run a continuity test on the temperature control thermostat to see if it is shorted. It is possible for it to have burned out electrical contacts and fail to power the compressor even if it powers the fan. If the thermostat is shorted, replace it.

2. Temperature Control Board

Check the control board that supplies voltage to the compressor and other cooling components. If there are burns or arcing, or even disconnections, the board cannot supply the required voltage to the compressor. Consequently, the compressor will not run. Before replacing the bard, ensure it is damaged. Let a qualified technician check and certify it is damaged.

3. Thermostat

Check the thermostat with a multimeter to determine whether or not it has continuity. If there is no continuity, the thermostat cannot keep an eye on the temperature of the air to know when it becomes warm. As a result, it cannot alert the control board to power the compressor so that the unit can cool the room. Replace the thermostat.

4. Refrigerant

The amount of refrigerant in the system can cause the compressor to stop working. If it is insufficient, the compressor will run more than usual and wear out too quickly. And if it is much more than the system needs, the compressor will not function as it should and eventually stops working. Ideally, hire a professional HVAC technician to check the refrigerant level and determine whether to add more or reduce it.

Other Possible Components to Cause the Problem Are:

1. Overload Protector

Using a multimeter, test the overload protector to check for continuity. If the overload has no continuity, it means it can no longer protect the compressor from overheating or burning out when it pulls too much current. The best solution is to replace the device.

2. Thermistor

Get a multimeter and check the continuity of the thermistor. If you find no continuity, replace the thermistor. The thermistor, which is a sensor fixed on the control board, detects the outside air temperature. With the results, it can alert the board to supply power to the compressor and fan to run and produce cool air. However, the compressor may stop running if the thermistor becomes faulty because then, it cannot provide accurate temperature results.

3. Selector Switch

The switch is that which the thermostat activates to send power to the cooling system when the air temperature rises. While it does not directly control the compressor, it can play a role in whether or not the motor runs if it is defective. So, press the selector and rotate the knob to see if the compressor runs. If it runs intermittently or not at all, replace the switch.

4. Capacitor

The capacitor must be in good working condition if the compressor must work. Place the probes of a multimeter on the terminals of the capacitor and run a continuity test. If the capacitor has no continuity, replace it. Otherwise, the compressor will not run at all; the capacitor stores power and provides it when the compressor needs to start and run.

5. Compressor

There is the possibility that the compressor is faulty, though this is hardly the case. Check other components that are more likely to become faulty before checking the compressor; it is quite expensive to replace if it is faulty. When other components are working yet the problem persists, test the compressor.

6. Boards

Check the relay and main control boards, but only after determining that nothing else is causing the problem. Many boards have been wrongly diagnosed and discarded, so it is recommended to eliminate other components before checking them.

LG Portable Air Conditioner Compressor Turns On and Off – Quick Fix

Check the timer, thermostat, air filter, condenser coil, and compressor itself if your portable air conditioner keeps turning on and off in short intervals. One or more of these parts is faulty and needs attention or replacement. This article explains how to troubleshoot each part and fix the faulty ones.

Why Does My LG Portable Air Conditioner Keep Shutting Off?

Check the water collection tank to see if it is full. When the tank is full, it throws a switch that turns the air conditioner off. Fortunately, it is pretty straightforward to empty the tank, especially if you have a ready floor drain close to it.

Typically, the tank should not fill up too quickly, so you may want to check if there is an open window or space through which hot air enters the room, increases humidity, and cause the tank to fill up too fast.

If the problem is not the collection tank, check to see if Energy Saver is activated. It is one of the modes in some LG air conditioners and it turns the compressor and fans off when the room temperature reaches a set point. It will turn the compressor on again when the temperature rises.

Use the Mode button to select the Cool mode of operation or any other one if the Energy Saver mode is not to your taste. You may also want to use the timer to increase the temperature and eventually turn off the air conditioner at night when the outside temperature drops.

One other possibility is that the unit is bigger than the room where it is placed. If the air conditioner’s BTU rating is larger than the square footage of the room, the compressor will frequently shut off. Consider trading the unit in for one with a BTU rating closer to your room size.

LG Air Conditioner Noisy Compressor – What to Do

When the compressor of an air conditioner becomes excessively noisy, the only repair is to replace it. What this means is that you should replace the entire air conditioning unit if it is more cost-effective than replacing the compressor alone.

A noisy compressor indicates it is wearing out. It may be that the pistons that turn refrigerant are stuck or there are loose screws. However, you can continue using the air conditioner with the noisy compressor if it continues working and you can bear the noise. 

Have a technician check its functionality to let you know how much longer the compressor will last. Sometimes, a noisy compressor lasts for years, so it may save you money to continue using it if the noise is bearable.

Quieten the Noise

Use a compressor blanket to dampen some of the noise from the compressor so that you can continue using it. A qualified HVAC technician can install it for you. A small fence around the condenser also helps to reduce the noise from the compressor. 

But you must keep in mind that the condenser needs space around it for proper air circulation to prevent overheating. So, do not put the fence too close to the unit if you are going for the fence option. 

One other option is planting bushes and shrubs around the condenser to reduce the noise. Again, create some space around the unit and always trim the bushes to prevent too much growth.


If your LG air conditioner has problems, it is crucial to find solutions as quickly as possible. We have discussed different possible problems an air conditioner compressor may have and how to fix them. However, contact LG Support Center to report any lingering compressor issue and request service. Alternatively, use the services of certified technicians for further assistance.

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