Name
Function
Notes
Specification
Check method
Symbol
(function)
Solenoid
valve
SV1
Discharge-
suction bypass
SV3
Discharge-
suction bypass
SV4a~4d
Heat exchanger
capacity control
SV5a, 5b
Heat exchanger
capacity control
21S4b
P450-P650
types only
P400-P650
types only
1
High/low pressure bypass at
starting and stopping, and capacity
control during low-load operation
2
High-pressure rise suppression
Provides compressor protection
when Compressor No. 2 is at a stop
SV2
Discharge-
suction bypass
Low-pressure down suppression
Controls outdoor unit heat exchanger
capacity.
Heats refrigerants in the compressor.
4-way
valve
21S4a
Switches between cooling and heat-
ing cycles.
Switches between cooling and heat-
ing cycles.
AC220~240V
Open when energized
Closed when not energized
AC220~240V
Closed when energized
Open when not energized
Resistance value
check
Continuity check
with a tester
Cord heater AC220~240V
CH11,CH12·····1280
Ω
45W
AC220~240V
De-energized : cooling cycle
Energized : heating cycle
Continuity check
with a tester
CH12 on
P450-P650
types only
1
273+t
R
0
=15k
Ω
R
0/80
=3460
Rt =
15exp{3460( - )}
1
273
0˚C : 15k
Ω
30˚C : 4.3k
Ω
10˚C : 9.7k
Ω
40˚C : 3.1k
Ω
20˚C : 6.4k
Ω
25˚C : 5.3k
Ω
CH11, 12
Crankcase
heater
Heater
Name
Function
Notes
Specification
Check method
Symbol
(function)
Linear
expansion
valve
Thermistor
LEV
TH1 (Suction air
temperature)
TH2 (Piping
temperature)
TH3 (Gas-side
piping
temperature)
TH4 (Outdoor air
temperature)
Temperature
sensor (Indoor
air temperature)
1
Adjusts superheat at the indoor
heat exchanger outlet during
cooling
2
Adjusts subcool at the indoor heat
exchanger outlet during cooling
1
Indoor unit control (Anti-
freeze/heat adjustment)
2
LEV control during heating
operation (subcool detection)
Indoor unit control (Thermo)
LEV control during cooling operation
(superheat detection)
Indoor unit control (Thermo)
Indoor unit control (Thermo)
DC12V
Opening of stepping motor
driving valve 0-(1400) pulses
Resistance value
check
Refer to the section
on continuity test
with a tester
Continuity between
white-red-orange
Continuity between
yellow-brown-blue
Yellow
M
Blue
Brown
White
Red
Orange
- 83 -
2. Indoor Unit