LG Air Conditioner - Heating While It says defrosting or pre heating in progress, heating is failed. Heating stops

1. Pre heating function is used to make sure that there is no cold wind coming out by raising the temperature of the pipe for the indoor unit when starting heating in the early phase.

2. Defrosting function is to melt frosts formed due to reducing temperature of the outdoor unit during heating operation.

※ Both pre heating and defrosting functions are normally operated to facilitate heating, so rest assured when you use it.

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How to check

1. During pre heating/defrosting operation, the pre heating/defrosting LED lamps are lit.

2. When entering the defrosting mode, the air conditioner briefly performs cooling operation to generate hot wind from the outdoor unit to melt frosts on the outdoor unit.
Now, in order to make sure there is no cold wind from the indoor unit, the indoor unit does remains off, and by minimizing the vane angle, generation of cold wind is prevented.

[Occurring in early phase of heating operation] Pre heating

Step 1. Pre heating operation to raise the temperature of the pipe for the indoor unit

During heating, it circulates warm refrigerant to the indoor to raise the pipe temperature and then start heating, thus there is no wind immediately.
If the surrounding temperature of the outdoor unit drops below -15°C(5℉), preheating might take longer than usual or lukewarm wind can come out.

Step 2. Pre heating displays when the indoor temperature reaches the target temperature

If the indoor temperature is higher than the target temperature, the wind will stop and the product is in waiting mode of pre heating.

[Occurring during heating operation] Defrosting

Step 1. Defrosting operation to melt ice of the evaporator for the outdoor unit

As opposed to cooling operation, during heating operation, the indoor unit generates hot wind and the outdoor unit generates cold wind.
Moisture from the air adheres to the cooled evaporator of the outdoor unit, thus forming ice, and in order to prevent degradation of the cooling performance due to freezing in the evaporator for the outdoor unit, defrosting operation starts.

Step 2. Defrosting operation to prevent ice forming of the evaporator for the outdoor unit

It is possible for defrosting operation to start automatically due to internal freezing or the pipe temperature that is not checked externally.

Frost occurs in the outdoor unit

During defrosting operation

Defrosting completed

[Air conditioner operation status during defrosting]

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This guide was created for all models, so the images or content may be different from your product.