Master And Slave Outdoor Unit Eev Control; Main Eev Control; Subcooling Eev Control; Avoiding Excessively High Discharge Temperatures - LG Multi V5 Service Manual

BASIC CONTROL
Master and Slave Unit EEVs / Fan Motor Control

Master and Slave Outdoor Unit EEV Control

Main EEV Control

Main EEV operates with fuzzy logic to keep the degree of superheat (about 37.4°F) at the evaporator outlet stable during heating mode.
Degree of Superheat = Tsuction - Tevaporation
where,
• Tsuction = Temperature measured at the suction pipe sensor (°F).
• Tevaporation = Evaporation temperature equivalent to low pressure (°F).

Subcooling EEV Control

Subcooling EEV operates with fuzzy logic to keep the degree of subcool (about 59°F) at the outlet of the subcooler stable during cooling
mode.
Degree of Subcool = Tcondensation - Tliquid
where,
• Tliquid = Temperature at the outlet of the subcooler (°F).
• Tcondensation = Condensation temperature equivalent to high pressure (°F).

Avoiding Excessively High Discharge Temperatures

After the main EEV opens to a predetermined amount (R410A: 800 pulses), and the discharge temperature is above 185°F in heating mode,
subcooling EEV control will operate to maintain compressor superheat.
Vapor Injection Flow Rate Control During Heating Mode
The degree of Superheat (VI_SH) = Subcooler out (°F) – Subcooler in (°F)
where
•
•
• 194°F > Td : VI_SH = 33.8°F
Fan Motor Control
Fan motor operates using Fuzzy logic.
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