Special Control; Defrost Control - LG Universal System Air Conditioner Service Manual

2. Special control

2.1 Defrost control

2.1.1 Starting to the defrosting operation
1) Defrost operation will be start when the conditions below are matched
a) Accumulation time of operation and the period after completion of defrost = 35 min.
b) After 10 minutes from re-starting the compressor .In case of being over 35 minutes of accumulated operating
time, defrosting operation starts after 10 minutes.
c) Piping temperature of the outdoor heat exchanger maintain below defrost starting temperature for 4 minutes
after 35 minutes continuous operation.
d)In case of passing 10 minutes after oil recovery operation
2) Outdoor piping temperature is below than –6 (Option) °C for starting defrosting operation.
2.1.2 Defrosting Control Algorithm
1) Lowering the compressor frequency when starts the defrosting operation.
Constant speed compressor is ON after 10 seconds from the arrival time of 30 Hz (Option) frequency and is
speed up its revolution till 100 Hz (Option)
2) Every LEV have 350 pulse (Option) of opening when starts defrosting operation.
3) Reversing valve is OFF after 5 seconds from arriving the compressor operating frequency of 30 Hz and then
fans of indoor units turn OFF.(including the indoor unit with being OFF except the remote controller is being
OFF)
4) After 5 seconds minutes from the time arriving 30 Hz, fans of outdoor unit turn OFF and Hot Gas bypass/Oil
separator valve turn ON.
2.1.3 Control algorithm of defrost completion
1) Frequency of compressor lowering to 30 Hz and maintain constant speed operation with 30 Hz for 75 seconds
and then stating operation. If the constant speed compressor is OFF, it will be receive OFF signal after 5 sec-
onds from the arrival time of 30 Hz.
2) The LEV will open with the standard previous pulse after 5 seconds from the time of 30 Hz.
3) Reversing valve is ON after 15 seconds from the time of 30 Hz of compressor frequency.
4) Fan of outdoor unit is ON with high speed and maintain it after 5 seconds from the time of 30Hz.
5) Hot Gas bypass valve/Oil separator bypass valve make OFF after 75 seconds from the time of 30Hz.
Outdoor Units
Service Manual 131