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[LG Air Conditioner - Heating] Airflow Stops and a Defrost, Preheat

※ Note : Both preheating and defrosting are normal operations designed to ensure efficient heating. Rest assured, your unit is working properly.

[LG Air Conditioner - Heating] Airflow Stops and a Defrost, Preheat, or Water Droplet Indicator Appears LG USA help image
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TroubleshootingAir Conditioners

What to Check First

  1. 1. Preheating raises the indoor unit's pipe temperature when heating first starts to prevent cold air from blowing out.
  2. 2. Defrosting melts any frost that forms on the outdoor unit while the heater is running.
  3. Step 1. Preheating to warm up the indoor unit When heating starts, warm refrigerant circulates to heat the indoor unit, so warm air does not come out immediately. If the temperature around the outdoor unit drops below -15°C (5°F), preheating may take longer than usual, or lukewarm air may blow for an extended period.
  4. Step 2. Preheating indicator turns on when the target temperature is reached When the room temperature exceeds the target temperature, the fan stops and the unit enters standby mode with the Preheating indicator on.
  5. Step 1. Defrosting to melt ice on the outdoor unit heat exchanger During heating, the indoor unit blows warm air while the outdoor unit blows cool air. Moisture in the air can freeze on the surface of the outdoor unit's heat exchanger. Because ice buildup on the heat exchanger reduces heating performance, the system automatically starts a defrost cycle to melt the ice.
  6. Step 2. Defrosting to prevent internal ice on the outdoor unit heat exchanger The defrost cycle may also run automatically based on internal piping temperature or ice buildup that isn’t visible.
  7. ※ Note : Both preheating and defrosting are normal operations designed to ensure efficient heating. Rest assured, your unit is working properly.
  8. ➔ If the target temperature is set too low, try raising it.
  9. When using the unit in heating mode in cold weather, the Defrost or Preheat indicator may light up on the display, and airflow may pause for a few minutes. This is a normal preheating step to make sure warm air comes out. Please wait a moment, and warm air will gradually start coming out.
  10. ※ Note: When heating first starts, if the unit’s piping temperature has not yet warmed up to 22℃ (72℉), the louvers will open but the fan will temporarily stay off. Even after the unit warms up and heating begins, the initial airflow may feel lukewarm or slightly cool because the air is still cooler than your body temperature.

Why This Can Happen

Symptoms can have more than one cause, and the correct steps depend on the exact model, installation and operating conditions. Use the checks above to narrow the issue before service.

Safety and Model-Specific Guidance

Stop troubleshooting if you notice burning, electrical damage, unsafe heat, gas odor, refrigerant concerns, or water near electrical components. Follow the official LG USA instructions for your exact model.

Frequently Asked Questions

What should I check first for [LG Air Conditioner - Heating] Airflow Stops and a Defrost, Preheat, or Water Droplet Indicator Appears?

1. Preheating raises the indoor unit's pipe temperature when heating first starts to prevent cold air from blowing out.

When should I stop troubleshooting and contact LG?

Stop if the product shows signs of electrical damage, burning, leaking near electrical components, or if the recommended checks do not resolve the issue. Use LG USA support for model-specific service guidance.

Does this guidance apply to every LG model?

Not always. Controls, error codes and service steps can differ by model. Confirm the exact model number and follow the linked LG USA article for model-specific instructions.

Related LG Products

These model pages are linked because the stored category or exact model matches this Help Library topic.

Buying Guides for This Product Type

Efficiency & running costAir Conditioner Efficiency, Energy & Running-Cost GuideHousehold use caseAir Conditioner Family & High-Use Household GuideFeatures & valueAir Conditioner Features Worth Paying For — Value GuideFit & installationAir Conditioner Fit, Installation & Delivery Planning

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Read the Official LG Guide