Electronic Inspirations: LG air conditioner troubleshooting, error codes and checks and repair procedure of the indoor unit

Do not touch, operate, or repair the product with wet hands. Holding the plug by hand when taking out. Otherwise there is risk of electric shock or fire.

Be sure to turn off power switch before connect or disconnect connector, or parts damage may be occurred.

Cooling & heating Operations

Cooling Mode

Operating frequency of compressor depends on the load condition, like the difference between the room temp. and the set temp., frequency restrictions.
• If the compressor operates at some frequency, the operating frequency of compressor cannot be changed within 30 seconds. ( not emergency conditions)
• Compressor turned off when
- intake air temperature is in between ±0.5°C of the setting temp. limit for three minutes continuously.
- intake air temperature reaches below 1.0°C of the temperature of setting temp..
• Compressors three minutes time delay.
- After compressor off, the compressor can restart minimum 3 minutes later.

Heating Mode

Operating frequency of compressor depend on the load condition, The difference between the room temp. and set temp., frequency restrictions.
• If compressor operates at some frequency, the operating frequency of compressor cannot be changed within 30 seconds.
• Condition of compressor turned off
- When intake air temperature reaches +4°C above the setting temperature.
• Condition of compressor turned on
- When intake air temperature reaches +2°C above the setting temperature.
* Condition of indoor fan turned off
- While in compressor on : indoor pipe temp. < 20°C
- While in compressor off : indoor pipe temp. < 30°C
• While in defrost control, between the indoor and outdoor fans are turned off.
• Compressor 2minutes delay
- After compressor off, the compressor can restart minimum 2 minutes later.

NOTE: Some Models are different by temperature of thermo ON/OFF.

CST/Duct/CVT type indoor unit matched with Universal Outdoor unit	CST/ Duct/CVT type indoor unit matched with Single Outdoor unit/Multi Outdoor unit/Multi V Outdoor unit
Thermo ON : +2 °C above setting temp. Thermo OFF : +4 °C above setting temp.	Thermo ON : Setting temp. Thermo OFF : +3 °C above setting temp.

Auto restart Operation

Whenever there is electricity failure to the unit, and after resumption of the power, unit will start in the same mode prior to the power failure. Memorized condition are on / off condition, operating mode (cooling/ heating), set temperature and fan speed. The unit will memorize the above conditions and start with same memorized condition.

Error Indicator (Outdoor)

Pump Down

1) Set the Dip Switch as follow after shutting the power source down.

2) Reset the power.
3) Red LED and Green LED of PCB lights during work.
(The indoor unit is operated by force.)
4) If operation is done, Red LED will be turned off.
If operation is not done normally, Red LED will blink.
5) Close the Liquid valve only after green LED turned off (7 minutes from the start of the machine).
Then close the gas valve after Green LED on.

* When the green LED of PCB is on, compressor is going to be off because of low pressure.
* You should return the Dip Switch to operate normally after finishing the operation.
* Improper Pump down will lead to product turn off along with LED (green &red) off with in 20 minutes from the initial start.

Connect the vacuum pump to the center hose of charge set center hose.

Evacuation for approximately one hour.
– Confirm that the gauge needle has moved toward 0.8Torr.

Close the valve (Lo side) on the charge set, turn off the vacuum pump, and confirm that the gauge needle does not move (approximately 5 minutes after turning off the vacuum pump).

Disconnect the charge hose from the vacuum pump.
– Vacuum pump oil.
If the vacuum pump oil becomes dirty or depleted, replenish as needed.

[Use a vacuum pump or inert (nitrogen) gas when doing leakage test or air purge. Do not compress air or Oxygen and do not use Flammable gases.
Otherwise, it may cause fire or explosion.
- Otherwise, it may cause personal injury.]

Gas Charging (After Evacuation))

Connect the charge hose to the charging cylinder.
– Connect the charge hose which you dis-connected from the vacuum pump to the valve at the bottom of the cylinder.
– If you are using a gas cylinder, also use a scale and reverse the cylinder so that the system can be charged with liquid.

Purge the air from the charge hose.
– Open the valve at the bottom of the cylinder and press the check valve on the charge set to purge the air. (Be careful of the liquid refrigerant). The procedure is the same if using a gas cylinder.

Open the valve (Lo side on the charge set and charge the system with liquid refrigerant.
– If the system cannot be charged with the specified amount of refrigerant, it can be charged with a little at a time (approximately 150g each time) while operating the air conditioner in the cooling cycle; however, one time is not sufficient, wait approximately 1 minute and then repeat the procedure (pumping down-pin).

[This is different from previous procedures. Because you are charging with liquid refrigerant from the gas side, absolutely do not attempt to charge with larger amounts of liquid refrigerant while operating the air conditioner.]

Immediately disconnect the charge hose from the 3-way valveʼs service port.
– Stopping partway will allow the gas to be discharged.
– If the system has been charged with liquid refrigerant while operating the air conditioner turn off the air conditioner before disconnecting the hose.

Mount the valve stem nuts and the service port nut.
– Use torque wrench to tighten the service port nut to a torque of 1.8 kg.m.
– Be sure to check for gas leakage.

[When installing or relocation the unit, make sure that no substance other than the specified refrigerant(R410A) enter the refrigerant circuit.
- Any presence of foreign substance such as air can cause an abnormal pressure rise and may result in explosion or injury.]

Trouble analysis

Check temperature difference between intake and discharge air, and check for the operating current too.

Temperature difference between intake and discharge air depends on room air humidity. When the room air humidity is relativery higher, temperature difference is smaller. When the room air humidity is relatively lower temperature difference is larger.

Check temperature and pressure of refrigeration cycle in cooling mode.

The suction pressure is usually 8.5~9.5kg/cm2G(Cooling) at normal condition.(R410A)
2. The temperature can be measured by attaching the thermometer to the low pressure tubing and wrap it with putty.

The Product doesn’t operate at all

Check the voltage of power supply (AC220V/AC240V, 50Hz) and check for the following:

The Compressor/Outdoor Fan don't operate