Skip to Contents Skip to Accessibility Help
Close

Help Library

Find help information for your LG product

  

Power Issues - Room Air Conditioner

Troubleshooting Air Conditioners Last Updated 10/11/2017
Power Issues - Room Air Conditioner

If the air conditioner does not power on, possible causes are; power outage in the home tripped the circuit breaker, the outlet that the unit is plugged into does not have power, or the unit may require a repair service.

  1. Select the type of air conditioner you have:




  2. Note: If you are having issues with a split unit or duct free air conditioner, they are considered business units and will not be covered in this article, please visit www.lg-dfs.com for further support.

Unit won't power ON.

If the air conditioner does not power on, possible causes are: power outage in the home tripped the circuit breaker, the individual outlet has no power, or the unit is defective.

  1. The air conditioner power plug has an indicator light which can be OFF (No Light), GREEN, or RED (orange).

    • Plug the air conditioner into the wall outlet.

    What is the STATUS (color) of the power plug INDICATOR LIGHT?

    OFF GREEN RED
  2. First check if the circuit breaker was tripped. Then, test if the outlet has power by plugging in another electric device besides the air conditioner.

    Is the outlet receiving power?

    Yes No
    • Press RESET on the power plug.

    • Power ON the air conditioner from the control panel.

    If the unit does not turn on, the air conditioner is not receiving power. The unit will require a repair service please visit our Request a Repair page.

    reset button
  3. The outlet is not receiving power. Contact an electrician for further assistance.

  4. The air conditioner IS receiving power.

    • Press the TEST button on the power plug.

    • Press the RESET button on the power plug.

    • Press the POWER button on the control panel.

    Did the air conditioner power on?

    Yes No
    reset and test button
  5. The air conditioner has a safety relay that may have been tripped causing the power OFF condition.

  6. The unit will require a technician to check the CONTROL PANEL, please visit our Request a Repair page.

    • Press RESET on the power plug. The indicator light should turn GREEN.

    • Press POWER on the air conditioner control panel.

    Did the air conditioner power on?

    Yes No
  7. Power should now be restored to the air conditioner.

  8. The unit will require a technician to check the POWER CORD, please visit our Request a Repair page.

Unit powers ON, but won't run.

  1. Is the unit powered on a dedicated circuit breaker?

    Yes No

    How to check - Method 1

    If you know what breaker the unit is powered from, you can trip the breaker at the breaker box. If other devices are WITHOUT power besides the air conditioner, then the unit is not on a dedicated circuit breaker.

    How to check - Method 2

    Turn off all other electrical devices in the room besides the air conditioner. If the unit runs fine with other devices turned off, then likely the unit is not on a dedicated circuit breaker.***

  2. Since the unit is on a dedicated breaker, we need to check the unit for adequate power supply.

    Proceed to Power Supply
  3. If the unit is not on a dedicated circuit breaker, the unit may power ON but not run. The reason is that the unit does not require as much power to display the settings, or even run the fan, but it does to turn on and run the compressor.

Portable air condition must be plugged into a grounded 60Hz, 120VAC, outlet protected by a 15amp time delay fuse or circuit breaker.

The outlet must be rated to provide the proper power level to the unit. If you only changed the outlet to match the power cord plug, but did not have the outlet rewired, then the unit will not be receiving the correct power.

Proceed to Mode Setting
  1. Let's check the control panel to verify that the unit is on the right setting.

    What mode is the unit currently running?

    COOL and TEMP setting set lower than ambient temperature Not set to COOL mode
  2. Did this occur while you were trying to use the TIMER function?

    Timer was set but unit didn't power on at the designated time Timer was not used
  3. Press the MODE key repeatedly until COOL mode is indicated on the control panel.

    • Unplug the power cord from the outlet.

    • Allow the unit to sit without power for 3 minutes before plugging it back in.

    • Press the POWER button and set the timer function to occur again. If the issue occurs again the unit may require a repair service. Please visit our Request a Repair page.

  4. Does the LED light on the display panel flicker continuously?

    Yes No
  5. This may be a sign that your unit requires a repair service. Please visit our Request a Repair page.

  6. We need to proceed to the next section of this article to check the unit's responsiveness or not cooling options.

    Proceed to Active Cooling

  1. Is the unit completely unresponsive?

    Completely unresponsive, even with correct outlet and power supply Fan runs, but the unit is not cooling?
  2. The unit will require a technician for further troubleshooting, please visit our Request a Repair page.

  3. This is a not cooling issue, please refer to our Not Cooling article.

Unit powers ON, but won't run.

  1. Is the unit powered on a dedicated circuit breaker?

    Yes No

    Test Method 1

    If you know what breaker the unit is powered from. You can trip the breaker at the breaker box. If other devices are WITHOUT power, then the unit is NOT on a dedicated circuit breaker.

    Test Method 2

    Turn off all other electrical devices in the room besides the air conditioner. If the unit runs fine with other devices turned off, then likely the unit is not on a dedicated circuit breaker.***

  2. Since the unit is on a dedicated breaker, we need to check the unit for adequate power supply.

    Proceed to Power Supply
  3. If the unit is not on a dedicated circuit breaker, the unit may power ON but not run. The reason is that the unit does not require as much power to display the settings, or even run the fan, but it does to turn on and run the compressor.

Check for adequate power supply.

Check the specifications for your model to determine the power requirements. Your model's power specification is described in the owner's manual. Visit our Manuals and Documents page to download your copy.

Unit requires a 208/230 volt.

The outlet must be rated to provide the proper power level to the unit. If you only changed the outlet to match the power cord plug, but did not have the outlet rewired, then the unit will not be receiving the correct power.

Unit uses a 115 volt.

If the outlet is receiving the correct power supply and is on a dedicated circuit, then we need to check the Mode settings following the link below.

Proceed to Mode Setting
  1. Let's check the control panel to verify the unit is on the right setting.

    What mode is the unit currently running?

    COOL and TEMP setting set lower than ambient temperature Not set to COOL mode
  2. Did this occur while you were trying to use the TIMER function?

    Timer was set but unit didn't power on at the designated time Timer was not used
  3. Press the MODE key repeatedly until COOL mode is indicated on the control panel display.

    • Unplug the power cord from the outlet.

    • Allow the unit to sit without power for 3 minutes before plugging it back in.

    • Press the POWER button and set the timer function to occur again. If the issue occurs again the unit may require a repair service. Please visit our Request a Repair page.

  4. Does the LED light on the display panel flicker continuously?

    Yes No
  5. This may be a sign that your unit requires a repair service. Please visit our Request a Repair page.

  6. We need to proceed to the next section of this article to check the unit's responsiveness or not cooling options.

    Proceed to Active Cooling
  1. Is the unit completely unresponsive?

    Completely unresponsive, even with correct outlet and power supply Fan runs, but the unit is not cooling?
  2. The unit will require a technician for further troubleshooting, please visit our Request a Repair page.

  3. This is a not cooling issue, please refer to our Not Cooling article.

Powers OFF and ON intermittently.

Air conditioners manufactured after 2010 contain a SAFETY RELAY, which automatically powers the unit OFF if the condenser overheats. After the unit cools down, the safety relay resets and normal operation should resume.

When the safety relay is active; the following scenario will be noticed:

Through the Wall and Window Units

The unit will shut off totally. The display, fan, and compressor will shut off.

Portable Units

The unit will shut down partially. The display and compressor will shut off, but the fan will continue to run.

If the safety relay frequently shuts the air conditioner off, check the following installation issues:

  1. Install the unit under shade.

    If the air conditioner is installed in direct sunlight, the air temperature around the air conditioner can cause the unit to overheat. Installing in a shaded area can resolve this issue.

    We recommend installing an awning or shade cover over the air conditioner to resolve the issue.

  2. Clear obstructions.

    Obstructions around the unit can block the airflow, causing the unit to overheat. Refer to the owner’s manual for proper clearance requirements.

    To maximize airflow and cooling performance, place the portable air conditioner as close to the center of the room as possible.

    distance from wall
  3. Clean the filter.

    Accumulation of dust and other debris on the filter and condenser can restrict airflow causing the unit to overheat.

    Regular maintenance on the air filter is recommended to prevent air flow from being blocked so the unit runs at peak efficiency. Please refer to our Regular Maintenance - Room Air Conditioner article for more information.

    clean filter

Powers OFF and ON intermittently.

Air conditioners manufactured after 2010 contain a SAFETY RELAY, which automatically powers the unit OFF if the condenser overheats. After the unit cools down, the safety relay resets and normal operation should resume.

When the safety relay is active; the following scenario will be noticed:

Through the Wall and Window Units

The unit will shut off totally. The display, fan, and compressor will shut off.

Portable Units

The unit will shut down partially. The display and compressor will shut off, but the fan will continue to run.

If the safety relay frequently shuts the air conditioner off, check the following installation issues:

  1. Install the unit under shade.

    If the air conditioner is installed in direct sunlight, the air temperature around the air conditioner can cause the unit to overheat. Installing in a shaded area can resolve this issue.

    We recommend installing an awning or shade cover over the air conditioner to resolve the issue.

    install a awning or shade
  2. Clear obstructions.

    Obstructions around the unit can block the airflow, causing the unit to overheat. Refer to the owner’s manual for proper clearance requirements.

    To maximize airflow and cooling performance, place the portable air conditioner as close to the center of the room as possible.

    remove obsstructions
  3. Clean the filter.

    Accumulation of dust and other debris on the filter and condenser can restrict airflow causing the unit to overheat.

    Regular maintenance on the air filter is recommended to prevent air flow from being blocked so the unit runs at peak efficiency. Please refer to our Regular Maintenance - Room Air Conditioner article for more information.

    clean filter

Trips circuit breaker OFF.

  1. Power recommendation.

    Portable air condition must be plugged into a grounded 60Hz, 120VAC, outlet protected by a 15amp time delay fuse or circuit breaker.

  2. Install unit on dedicated circuit.

    If the outlet has the correct voltage, but the breaker is tripping and causing the loss of power, we can preform a simple test to see if other devices are powered on the same circuit as your air conditioner.

    • Turn off all other electrical devices in the room besides the air conditioner.

    • If the unit runs fine with other devices turned off, then likely the unit is not on a dedicated circuit breaker.

    • If the unit is NOT on a dedicated circuit breaker, the unit may power on but not run.

      The reason for this is the unit does not require as much power to display the settings, or even run the fan, as it does to turn on and run the compressor. The A/C must be on a dedicated circuit breaker and not share with other outlets.

Trips circuit breaker off.

  1. Power recommendation.

    Check if the unit have an adequate power supply, the two scenarios below are the most common.

    Unit requires a 208/230 volt.

    The outlet must be rated to provide the proper power level to the unit. If you only changed the outlet to match the power cord plug, but did not have the outlet rewired, then the unit will not be receiving the correct power.

    Unit uses a 115 volt.

    The outlet has the correct voltage, but the breaker is tripping and causing the loss of power. We can to perform a simple test to see if other devices are powered on the same circuit as your air conditioner.

    NOTE: Check the specifications for your model to determine the power requirements. Your model's power specification is described in the owner's manual. Visit our Manuals and Documents page to download your copy.

  2. Install unit on dedicated circuit.

    AC units are built to operate on a dedicated circuit. Test the unit with other appliances in the room to know if its running on a dedicated circuit.

    • Turn off all other electrical devices in the room besides the air conditioner.

    • If the unit runs fine with other devices turned off, then likely the unit is not on a dedicated circuit breaker.

    • If the unit is NOT on a dedicated circuit breaker, the unit may power on but not run.

      The reason for this is the unit does not require as much power to display the settings, or even run the fan, as it does to turn on and run the compressor. The A/C must be on a dedicated circuit breaker and not share with other outlets.

Turns OFF abnormally.

  1. Are there any items nearby to the AC unit that are obstructing air flow?

    Yes No
    obstructed portable unit
  2. Move plants or curtains that will block airflow area from the front grill of the unit. The unit must also have enough room in the back for the exhaust to dissipate in order to work effectively. Blocked air flow could cause the unit to overheat and shut down during normal operation.

    blocked portable unit
  3. Have the air filter and coils been cleaned?

    Yes No
  4. We need to check for POWER LOSS on your unit, click the button below to proceed to the POWER LOSS section.

    Proceed to Power Loss
  5. The air filter should be cleaned once every two weeks and the coils should be checked periodically for dust buildup. Dirty air filters or coils will restrict airflow which will reduce cooling performance. Also this may restrict airflow enough for the unit to overheat and cause the unit to shut down during normal operation.

    Evaporator Coils

    • Remove the front grill.

    • Use a brush attachment with a vacuum cleaner to clean up any dust or debris that has made it past the air filter.

    • If you are cleaning the coils after the air conditioner has already been running, put the unit in fan mode for about an hour in order to allow any condensed moisture on the evaporator coils to dry.

    Condenser Coils

    • Use a soft bristled brush to gently brush the condenser coils while rinsing them off with a water hose pipe.

    • Remove any garden sprayer attachments and allow the water to flow directly from the end of the hose down over the coils to wash away dirt and debris.

    • The brush will loosen any build up that may have dried onto the coils.

    NOTE: The fins are sharp so take care when cleaning them. Do NOT bend the fins. If this happens accidentally you can purchase a fin comb from a local hardware store. The fin comb can be used to straighten any bent fins.

    For full maintenance information about your specific model, refer to your owner's manual for detailed information. Please visit our Manuals and Documents page to download a copy.

  1. Does the unit completely lose power (completely unresponsive to controls) or just stop running?

    Completely Loses Power Just Stops Running
  2. Sometimes, when the air condition loses power, it causes the home's circuit breaker to trip. Let's check the next section for further troubleshoot.

    Proceed to Breaker Trip
  3. If the unit simply stops running, this could be the result of the unit being in the wrong mode of operation. Check the control panel to see what mode the unit is currently operating.

    Set Unit to Cool Mode

    Press the mode key on the panel until COOL is selected. You may need to adjust the TEMP setting keys to a temperature setting lower than the current room temperature.

    Dail Type Controls

    Make sure the dial is set to COOL, and raise it to a higher cooling level (higher number).

  1. Does the breaker trip off when the unit loses power?

    Yes, breaker trips No, Check AFCI
    • Turn off all other electrical devices in the room besides the air conditioner.

    • If the unit runs fine with other devices turned off, then likely the unit is not on a dedicated circuit breaker.

    • If the unit is not on a dedicated circuit breaker, the unit may power on but not run.

      The reason for this is the unit does not require as much power to display the settings, or even run the fan, as it does to turn on and run the compressor. The A/C must be on a dedicated circuit breaker and not share with other outlets.

  1. Was the power lost because the AFCI (arc fault circuit interrupter) tripped on the power cord?

    Yes, AFCI is Tripped No, AFCI hasn't Tripped afci power cord
  2. Most newer models will have a green LED indicator light on the back of the power cord. If the green light is not illuminated, then press the RESET button on the power cord to restore power.

    NOTE: The AFCI device should be tested on a periodic basis by first pressing the TEST button and then the RESET button. If the TEST button does not trip or if the RESET button will not stay engaged, discontinue use of the air conditioner, it will require a repair service, please visit our Request a Repair page.

  3. If the AFCI hasn't tripped and the unit still will not power on, the unit will require a repair service. Please visit our Request a Repair page.

Turns OFF abnormally.

  1. Are there any items nearby to the AC unit that are obstructing air flow?

    Yes No
    obstructed portable unit
  2. Move plants or curtains that will block airflow area from the front grill of the unit. The unit must also have enough room in the back for the exhaust to dissipate in order to work effectively. Blocked air flow could cause the unit to overheat and shut down during normal operation.

    blocked portable unit
  3. Have the air filter and coils been cleaned?

    Yes No
  4. We need to check for POWER LOSS on your unit, click the button below to proceed to the POWER LOSS section.

    Proceed to Power Loss
  5. The air filter should be cleaned once every two weeks and the coils should be checked periodically for dust buildup. Dirty air filters or coils will restrict airflow which will reduce cooling performance. Also this may restrict airflow enough for the unit to overheat and cause the unit to shut down during normal operation.

    Evaporator Coils

    • Remove the front grill.

    • Use a brush attachment with a vacuum cleaner to clean up any dust or debris that has made it past the air filter.

    • If you are cleaning the coils after the air conditioner has already been running, put the unit in fan mode for about an hour in order to allow any condensed moisture on the evaporator coils to dry.

    Condenser Coils

    • Use a soft bristled brush to gently brush the condenser coils while rinsing them off with a water hose pipe.

    • Remove any garden sprayer attachments and allow the water to flow directly from the end of the hose down over the coils to wash away dirt and debris.

    • The brush will loosen any build up that may have dried onto the coils.

    NOTE: The fins are sharp so take care when cleaning them. Do NOT bend the fins. If this happens accidentally you can purchase a fin comb from a local hardware store. The fin comb can be used to straighten any bent fins.

    For full maintenance information about your specific model, refer to your owner's manual for detailed information. Please visit our Manuals and Documents page to download a copy.

  1. Does the unit completely lose power (completely unresponsive to controls) or just stop running?

    Completely Loses Power Just Stops Running
  2. Sometimes, when the air condition loses power, it causes the home's circuit breaker to trip. Let's check the next section for further troubleshoot.

    Proceed to Breaker Trip
  3. If the unit simply stops running, this could be the result of the unit being in the wrong mode of operation. Check the control panel to see what mode the unit is currently operating.

    Set Unit to Cool Mode

    Press the mode key on the panel until COOL is selected. You may need to adjust the TEMP setting keys to a temperature setting lower than the current room temperature.

    Dail Type Controls

    Make sure the dial is set to COOL, and raise it to a higher cooling level (higher number).

  1. Does the breaker trip off when the unit loses power?

    Yes, breaker trips No, Check AFCI
    • Turn off all other electrical devices in the room besides the air conditioner.

    • If the unit runs fine with other devices turned off, then likely the unit is not on a dedicated circuit breaker.

    • If the unit is not on a dedicated circuit breaker, the unit may power on but not run.

      The reason for this is the unit does not require as much power to display the settings, or even run the fan, as it does to turn on and run the compressor. The A/C must be on a dedicated circuit breaker and not share with other outlets.

  1. Was the power lost because the AFCI (arc fault circuit interrupter) tripped on the power cord?

    Yes, AFCI is Tripped No, AFCI hasn't Tripped afci power cord
  2. Most newer models will have a green LED indicator light on the back of the power cord. If the green light is not illuminated, then press the RESET button on the power cord to restore power.

    NOTE: The AFCI device should be tested on a periodic basis by first pressing the TEST button and then the RESET button. If the TEST button does not trip or if the RESET button will not stay engaged, discontinue use of the air conditioner, it will require a repair service, please visit our Request a Repair page.

  3. If the AFCI hasn't tripped and the unit still will not power on, the unit will require a repair service. Please visit our Request a Repair page.

Turns ON every couple of minutes.

The unit will turn off and on every couple of minutes if it is running on ENERGY SAVER MODE, or the unit is installed in a room smaller to the capacity size of the unit.

  1. Energy Saver is Active

    Energy saver mode will allow the unit to run until the desired room temperature is reached. Once that has been met, the unit will TURN OFF both the compressor and circulation fan.

    After that the circulation fan will cycle on approximately every 3 minutes to test the room air to determine if active cooling needs to resume.

    If this is too disruptive, you may consider swapping the unit to COOL mode. If this is mainly an issue during night time hours, you may want to consider setting an OFF timer to shut the unit down after you’ve fallen asleep and the outside temperature has cooled down for the night.

  2. Unit's size compared to room size.

    An air conditioner that has a BTU ratting for a large room will not work efficiently in a space that is too small. If a large capacity unit is placed in a room that is too small, cool air blowing out of the vents will lower the temperature of the room too rapidly causing the unit to stop active cooling. This leads to the unit cycling on and off very frequently because the unit is overpowered relative to the size of the room it’s in.

Author - Sanmi Ajanaku

Sanmi is a Home Appliance expert and author of this help library article. Please leave him feedback below about the page.

Article Feedback

Q1. Overall, how satisfied were you with the usefulness of this information?
1 2 3 4 5
Q1-1. Why were you dissatisfied with the usefulness of this information?
Q2. How would you improve the information?

Characters left : 500 / 500