Daikin VRV III REYQ8PY1, Service Manual

Page: 129 / 452

Special Control Si37-701
118 Function
3.4 Defrost Operation
[Start conditions]
Referring to the following conditions, start defrost operation.
• When there is a decrease in the coefficient of heat transfer of outdoor unit heat exchanger
• When there is a drop in the temperature of outdoor unit heat exchanger outlet (Tb)
• When the low pressure stays low for a certain amount of time (2 hours minimum)
Furthermore, the thermal conductivity of outdoor unit heat exchanger is calculated by Tc, Te, and compressor loads.
Defrosting outdoor unit actuator
Symbol
Elect.
symbol
Defrost operation Operation after defrost
REYQ REMQ
Compressor 1
—
M1C M1C REYQ8•10•12P: 232Hz+ON
REYQ14•16P: 232Hz+232Hz
REMQ8P: 210Hz
REMQ10•12P: 210Hz+ON
REMQ14•16P: 202Hz+ON+ON
REYQ8•10•12P: upper limit
124Hz(STD Holds)
REYQ14•16P: 232Hz+232Hz
REMQ8P: 210Hz
REMQ10•12P: 210Hz+ON
REMQ14•16P: 210Hz+ON+ON
Compressor 2 M2C M2C
Compressor 3 — M3C
Outdoor unit fan 1
—
M1F M1F
Outdoor unit fan 2 M2F M2F
Four way valve (for heat changer
selection)
20SA
Y2S
Y9S
Y3S OFF OFF
Four way valve (for high- and low-
pressure gas pipe selection)
20SB Y8S Y2S Holds Holds
Electronic expansion valve (main) EVM
Y1E
Y3E
Y1E 1375pls 0pls
Electronic expansion valve
(subcooling)
EVT
Y2E
Y5E
Y3E SH control 0pls
Electronic expansion valve
(refilling refrigerant)
EVJ Y4E Y2E 80pls 80pls
Solenoid valve (main bypass) SVE
Y5S
Y10S
Y6S ON OFF
Solenoid valve (hot gas) SVP Y4S Y5S OFF OFF
Solenoid valve (liquid pipe of
refrigerant regulator)
SVL Y3S Y4S 0pls 0pls
Solenoid valve (gas discharge
pipe of refrigerant regulator)
SVG Y1S Y1S 0pls 0pls
Solenoid valve (drain pipe of
refrigerant regulator)
SVO Y7S Y7S 0pls 0pls
Solenoid valve (discharge pipe of
refrigerant regulator)
SVT Y6S Y8S 0pls 0pls
End conditions
REYP8 to 16P (by unit)
•
6 min. and 30 sec.
•
Tb > 11°C continues for a
period of 90 consecutive sec.
•
Pc_max > 3.04MP
REMQ8 to 12P (by unit)
•
5 min. and 30 sec.
•
Tb > 11°C for a period of
10 consecutive sec.
•
Pc_max > 3.04MPa
REMQ14 and16P (by unit)
•
5 min. and 30 sec.
•
Tb > 11°C for a period of 30
consecutive sec.
•
Pc_max > 3.04MPa
•
30 sec.
•
Pc_max>3.04MPa
&
Pcmax>2.45MPa
Pcmax>3.04MPa
Pcmax<2.36MPa
Pcmax<2.95MPa
FANSTEP4
FANSTEP6
OFF
Pcmax>2.45MPa
Pcmax>3.04MPa
Pcmax<2.36MPa
Pcmax<2.95MPa
FANSTEP4
FANSTEP6
OFF
or
or
or
or